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Zoology Y2 > BIS204 Invertebrates > Flashcards

BIS204 Invertebrates Flashcards

1
Q

Animals have to solve the same problems in order to survive

A

-Get food and oxygen
-Maintenance of water and salt balance
-Removal of wastes
-Reproduction

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2
Q

Why are molluscs grouped close to annelids?

A

Due to trochophore (free-swimming) larval stage

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3
Q

Mollusc circulatory system

A

Open, haemocoel (blood system and coelom)
Oxygenated blood in heart pumped around coelom
Once deoxygenated, makes its way back to vessels in gills where it is oxygenated
Returns to vessels in the heart

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4
Q

Mollusc groups

A

Gastropods, bivalves, cephalopods

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5
Q

Body design necessary to meet survival problems correlates with 4 factors:

A

-Body design
-Size of animal
-Mode of existence
-Constraints of the genome

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6
Q

Aphotic zone

A

-No light, no photosynthesis
-Animals require other strategies than consuming phytoplankton
-Contains abyssal plane and Mariana trench

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7
Q

Terms to describe marine organisms

A

Pelagic- suspended or swimming
Benthic- bottom
Errant- mobile
Sessile- attached
Sedentary- unattached, immobile

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8
Q

What happens to pressure and temperature as you go deeper into the ocean?

A

Pressure increases and temperature decreases

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9
Q

Advantages of the sea

A

-Space
-High productivity
-Relatively constant
-Ocean water moves constantly due to wind and Earth’s rotation
-Isosmotic with body tissue fluids of many animals, meaning no complex osmoregulation required
-Buoyancy (can support large animals due to water density)
-Ammonia dissolves in water, so can be expelled as waste
-Allows for external fertilisation

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10
Q

Productivity of ocean

A

-(28 x 10^9 tons c/yr)
-Mainly photic zone

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11
Q

Where is ocean productivity highest?

A

Near continental shelves and coastlines, due to photosynthesis able to happen and nutrient run-off from land and freshwater

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12
Q

Constants of the ocean

A

-Temperature (high surface heat capacity, large volume and SA)
-Salinity is 3.4-3.7% (-3.5 in deep sea), low rainfall and high temperatures lead to high salinity, such as in the Arabia gulf
-Oxygen (highest in top 100m due to photosynthesis)
-pH is 7.8 (slightly alkaline due to CO2 dissolving, which is becoming an issue)

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13
Q

Estuarine environment

A

-Includes salt marshes (temperate) and mangroves
-Salinity <3.5%, as seawater mixes with freshwater
-Productive
-Only habited by specific organisms
-Seasonal variations
-Fertilisation depends on organism
-Waste can still be expelled as ammonia
-Support is still provided

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14
Q

Terrestrial environment features

A

-Daily and seasonal temperature extremes
-Oxygen uptake requires moist surface, but oxygen is constant
-Can suffer water loss, a big issue with animals
-No support for bigger animals
-Internal fertilisation required and eggs must be protected
-Ammonia will not dissolve, so waste is urea or uric acid

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15
Q

SA : Volume ratios

A

-As body size increases, the ratio decreases
-Small animals have large SA : Volume ratios, diffusion may be possible for gaseous exchange and waste removal etc., but can dry out easily
-Large animals have small ratios and require other mechanisms such as excretory and circulatory systems

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16
Q

What are genome constraints?

A

Limitations imposed by ancestral design controlled by animal’s genetic make-up (molluscs are incredibly diverse, but have the same body plan)

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17
Q

Pellicle in protozoans

A

-Cytoskeleton and membrane of protozoans
-Cytoplasm determines rigidity and flexibility
-Equivalent to cell wall

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18
Q

Test in protozoans

A

-Hard exterior of some protozoans
-Made by substances secreted by the organism or materials from surroundings

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19
Q

Locomotion in protozoans

A

-Using flagella (usually two) to propel organism forward by undulating
-Cilia are shorter, more abundant and can cover whole organism, beating in a metachronal wave, flopping to return to position
-Pseudopodia

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20
Q

Acquisition of food in protozoans

A

-Pinocytosis, small food particles engulfed into a vacuole
-Receptor mediated endocytosis, receptors on membrane detect and pick up specific foods
-Phagocytosis for large food particles, various receptors
-Oral groove (cytostome) is a specific area for eating

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21
Q

Reproduction in protozoans

A

-Different strategies among groups
-Asexual haploid
-Haploid adults with zygotic meiosis
-Diploid cycle
-Haplodiploid cycle

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22
Q

What controls protozoan cell water content?

A

Contractile vacuole

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23
Q

Examples of protozoans

A

-Amoebozoa
-Apicomplexans
-Trypanosomes
-Ciliates

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24
Q

Features of amoebozoa

A

-Found in damp environments due to high SA : volume ratio meaning water loss through osmosis
-Most free living, some parasitic

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25
Q

Parasitic amoebozoa

A

-Entamoeba dispar and colis
-Entamoeba histolytica

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26
Q

Commensalism

A

The term commensalism refers to a type of relationship between two different organisms that “eat from the same dish”

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27
Q

Apicomplexans

A

-Parasites
-Apical complex made of different cells found on top of organism that is used to latch on to host cells and enable parasite to be taken up by host cells
-Plasmodium
-Toxoplasma

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28
Q

Plasmodium

A

-Most deadly is falciparum
-Mosquito acts as a vector but also enables reproduction of plasmodium, making mosquito the definitive host
-Infected mosquito bites human
-Sporozoites from salivary glands enter human bloodstream and make way to liver
-Undergo many divisions (schizogony) to form merozoites that infect red blood cells
-Some develop into gametocytes, the final stage
-Gametocytes taken up by mosquito and gather in gut to form a zygote
-Zygote immediately undergoes meiosis to form more sporozoites that go to salivary glands
->1/2M deaths/yr, mostly children, 95% in Africa

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29
Q

Trypanosoma brucei

A

-Causes sleeping sickness
-Infects hoofed animals
-Has flagellum
-Kinetoplast full of mitochondrial DNA
-Has a variant surface glycoprotein (VSG) that triggers immune response in animal
-Animal produces antigens in response
-Can alter its VSG to evade immune system of animal
-Uses tsetse fly as vector, infected ones feed more
-Suggestion that zebra stripes are protection against tsetse flies by disrupting polarized light omitted by water
-Gambiense subsepcies fly-human-fly, death 2-3 years
-Rhodesiense is fly-game-fly, zoonosis and death 6-18 weeks

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30
Q

Toxoplasma gandii

A

-Life cycle involving cats and rodents
-Reproduces in cats, the definitive host
-Rodent is intermediate host, or vector
-Evidence that parasite manipulates host to lose fear of cats, meaning more are eaten and passed back to cats
-Suggested that 50% of human population infected
-Can affect unborn babies and possibly behaviour of adults

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31
Q

Trypanosomes

A

-Parasitic
-Trypanosoma brucei
-Ciliates

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32
Q

Ciliates

A

-Covered in cilia
-Aquatic/damp environments
-Most free living, some symbionts or parasites
-Contain micronuclei for sexual reproduction by conjugation (cells attaching and transferring genetic material) and macronuclei for asexual reproduction by binary division
-Can be attached

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32
Q

How and when did metazoans come to being?

A

-Approx. 700 MYA
-Individual cells grouped in a colony began coordinating their roles e.g. reproduction and feeding
-Each individual is now dependent on each other
-Known as colonial theory

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33
Q

Evidence for colonial theory of metazoan origin?

A

-Flagellated cells found in metazoans
-Many flagellates form colonies
-Molecularly, some flagellates do express certain genes that can be found in metazoans
-Choanoflagellates are most closely related unicellular relatives of animals

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34
Q

Choanoflagellates

A

Similar to sponges, live in aquatic and waterlogged systems

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35
Q

Phylum Porifera

A

Sponges

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36
Q

Features of sponges

A

-Simple structure with cellular level of operation and no tissues or organs
-Successful and widespread across aquatic ecosystems
-Variety of forms depending on where they are found

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37
Q

Origin of sponges

A

-Possible fossils found from 640-650 MYA
-Origin debated, used to be known as parazoa due to differences to other animals and separated on phylogenies
-It is now debated that other animal groups should be in that place

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38
Q

Are sponges completely sessile?

A

-No, they move very slowly (capable of moving 4mm per day)
-Can latch on to other animals
-Can perform ‘sponging’
-Were thought to be plants until 1700s

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39
Q

What is sponging?

A

-Animals such as bottle-nosed dolphin carry sponges on their mouths to help forage
-Fragments fall off and can regenerate

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40
Q

Sponge varieties

A

-Intertidal zone is used to wave action and food availability, so sponges are encrusted, flat and low growing
-Deeper water has less water movement and food availability so sponges are larger

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41
Q

Basic sponge structure

A

-Pinacytes form a pinacoderm (outside layer)
-Porocytes are holes throughout the sponge that come to the spongocoel
-Entrance to porocyte is called an ostium (incurrent pore)
-Lining the sponge are choanocytes
-Flagellum
-Amoebocytes crawl around, performing various tasks
-Mesohyl

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42
Q

Sponge water intake

A

-Ostium allows water into the sponge
-Water then leaves through osculum

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43
Q

Job of choanocytes

A

Used to take up food as sponge moves

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44
Q

Role of sponge flagellum

A

-Flap to generate a current through sponge
-Water passes through at up to 20,000 times the sponge’s volume in 24 hours
-Rate that flagella beat at can change
-Respond to stimuli, and (using myocytes (similar function to muscle cells)) can close osculum by contracting to pull it in
-Closure of osculum is to avoid drying out or to protect

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45
Q

Sponge amoebocyte function

A

-Gather up food
-Clean up outside of sponges
-Totipotent
-Secrete spicules

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46
Q

Sponge spicules function

A

-Form skeleton of sponge
-Some calcareous, some siliceous, some spongin (protein), or silicate spongin (CaCO3)
-Give internal structure and hold pores open
-Protect

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47
Q

Mesohyl of sponge

A

Forms inside ‘body’ and contains spiracles

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48
Q

Glass sponge features

A

-Found in deep sea
-Cannot close osculum, fixed shape
-75% of tissues are syncytial
-Produce electrical impulses
-Made of very fine silicate spicules
-Pairs of shrimps live inside sponge and get trapped during aduthood

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49
Q

Syncytial

A

No cell boundaries, masses of cells in sheets

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50
Q

Glass sponge electrical impulses

A

-Travel across sponge
-Control beating of choanocytes
-Can protect, e.g. if stimulated by sediment, beating is stopped and no sediment is taken up
-Not found in other sponges

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51
Q

Glass sponge silicate spicules

A

-Spicules go up, down and diagonal in patterns
-Many buildings have similar structures
-It increases strength

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52
Q

How do sponges feed?

A

-Most are filter feeders
-Some are carnivorous
-Sponges help coral reefs thrive in ocean deserts

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53
Q

Sponge filter feeding

A

-Small items such as bacteria
-Trapped by choanocytes and engulfed by amoebocytes
-Products transported through sponge

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54
Q

Some carnivorous

A

-Usually in deep sea as less food available
-E.g., harp sponges he modified spicules to trap prey such as shrimp

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55
Q

How do sponges help coral reefs thrive in ocean deserts?

A

-Help recycling of nutrients such as nitrogen and phosphorous
-Take up organic material produced by reefs
-This makes them accessible to other animals as parts of sponge drop off and can be eaten

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56
Q

Sponge reproduction

A

-Regeneration
-Some asexual reproduction
-Some sexual reproduction

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57
Q

Sponge regeneration

A

-Worked on by Wilson in early 1900s
-When pushed through a sieve they were able to reform
-When two sponges pushed through sieve, two were formed, showing that sponges can recognise own cells

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58
Q

Asexual reproduction in sponges

A

-Budding (small bit will drop off and form new sponge)
-By gemmules (little structure that pops out of sponge)

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59
Q

Sponge gemmules

A

-If harsh conditions arrive, gemmules are stimulated
-They are surrounded by spicules and filled with amoebocytes
-They stay resting until conditions return, when the amoebocytes are released to form a new sponge

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60
Q

Sexual reproduction in sponges

A

-Most hermaphrodite
-Do cross fertilise
-Gametes form as response to environment changes
-Sperm and eggs produced at different times to prevent self-fertilisation
-Sperm are expelled via osculum and engulfed by choanocytes (collar cells) of another sponge that transfer sperm to egg by losing flagellum and moving into the sponge
-Larvae are retained until the blastula stage, where they are released to swim around until finding a suitable environment to metamorphise

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61
Q

Sponge symbioses

A

-With zooanthellae
-With bacteria

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62
Q

Sponge - zooanthellae (algae) relationship

A

-Also seen in corals
-Algae are photosynthetic, so sponge gains photosynthetic pigments
-Different colours formed by symbiosis are used as a warning of toxicity to other organisms as protection
-Sponges provide nutrients for the algae

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63
Q

Sponge - bacteria relationship

A

-Sponges generate help with nutrient processing
-Some generate secondary metabolites, some of which have antibacterial/antiviral activity and can be harvested for medical use
-Some produce biotoxins that kill other organisms, preventing competition and killing organisms growing on it

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64
Q

Platyhelminthe basic structure

A

-Trpoblastic
-Bilaterally symmetrical
-Cephalisation
-Dorso-ventrally flattened
-Have organs
-75% are parasitic, with the free-living forms in freshwater
-Hermaphrodites

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65
Q

Triboblastic (acoelomate) meaning

A

-Gut in middle, surrounded by endoderm
-Solid mesoderm
-Ectoderm on outside
-No body cavity

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66
Q

Cephalisation

A

Concentration of nervous tissue in the anterior end

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67
Q

Positives and negatives of dorso-ventral flattening

A

-Can use diffusion (thus respiration)
-Prone to drying out

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68
Q

Platyhelminthes eating and digesting

A

-Pharynx is in middle of animal and is inserted into food and produces digestive enzymes
-Both extra- and intra- cellular digestion
-Gut has one opening
-Simple excretory system (protonephridia)

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69
Q

Platyhelminthes movement

A

-Can use longitudinal muscles to move
-Some acquire nematocysts from prey

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70
Q

Platyhelminthe nervous system

A

-Simple eye spots to detect light and dark to stay away from surface and avoid drying out
-Have oracles that detect chemicals
-Longitudinal nerves run along bodies

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71
Q

Platyhelminthe regeneration

A

-Further down the animal that you chop, the longer it takes to regenerate a head
-If a thin slice is made, two heads are grown (Janus head)
-Totipotent cells are known as neoblasts, and respond to a chemical gradient and tells the animal if it is a head or tail end
-Asexual reproduction thus possible

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72
Q

Patyhelminthes biochemical memory?

A

-Thompson and McConnell 1950s and 60s
-Paired bright light and electric shock
-Showing light without electricity caused animals to react as if electric shock had occurred
-Chopped up worms also responded this way
-McConnell suggested memory transferred chemically but results never reproduced
-More recent experiments trained them to not move from bright lights and empty space, which continued after chopping and regenerating

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73
Q

Sexual reproduction in platyhelminthes

A

-Mutual exchange of sperm or penis fencing in free-living form
-Many do not want the responsibility of having to be impregnated
-Worms then fight in order to pass sperm on without being impregnated

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74
Q

What adaptations did platyhelminthes evolve to become parasitic?

A

-Loss of unwanted organs such as gut, sensory organs
-Penetration devices to get into host such as hooks
-Attachment devices such as hooks and suckers
-Protective devices from digestion such as a covering, mucus, enzymes and chemicals
-Transmission via a vector
-Production of eggs in large numbers

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75
Q

Flukes (trematodes) features

A

-Tegument (non-ciliated syncytium)
-Suckers (oral and ventral)
-Simple gut
-Nervous system present
-Protonephridia also present

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76
Q

Reproduction in flukes

A

-Lots of reproductive tissue
-Reproductive system produces 10,000-100,000 times more eggs than free-living flatworms
-Usually hermaphrodite
-Mutual copulation

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77
Q

Annelid basic structure

A

-Blood system to transport fluids
-Coelom with hydrostatic skeleton
-Metemeric segmentation
-Closed circulatory system
-Epidermis covered by cuticle for protection

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78
Q

Role of coelom in annelids

A

-For transport
-Gut moves independently of body wall
-Site for gamete maturation

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79
Q

Annelid hydrostatic skeleton

A

-Water incompressible; base against which muscles can contract
-Circular muscles round outside are long and thin
-Longitudinal muscles are short and fat
-Muscles work antagonistically, creating peristalsis

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80
Q

Annelid locomotion using peristalsis

A

-An anchor is created, where longitudinal muscles contract
-Circular muscles then contract at opposite end
-This forms waves of contractions
-Penetration anchor prevents back slipping
-Terminal anchor allows trailing part of body to be pulled forward

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81
Q

Metameric segmentation

A

-Locomotion more efficient and precise
-Some structures run length of animal, some repeated in each segment such as nephridia and the excretory system
-Segments divided internally by septa
-Proliferation zone is where new segments are added

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82
Q

How may metameric segmentation be modified in annelids?

A

-Restriction of structures to particular segments, e.g., sensory apparatus in head, reproductive tissue in certain segments
-Some segments develop special structures such as swimming and sensory structures
-Segments may fuse together

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83
Q

Annelid excretory system

A

-Substances passed out through blood vessel walls by contraction
-Taken up by nephanephridium, where useful substances are absorbed and waste is expelled

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84
Q

Annelid groups

A

-Polychaeta (predominantly marine)
-Oligochaeta, including hirudinae (leeches) and clitellata

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85
Q

Polychaeta features

A

-Parapodia (pair of fleshy projections to increase SA) and lots of setae (bristle like structures for movement)
-Protomium (head end) well developed
-Nuchal organs also present

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86
Q

Errant vs sedentary polychaeta

A

-Errant e.g. Nereis (ragworm) move around a lot, active, developed head etc
-Sedentary example 1, Sabella (fanworm), a suspension feeder, uses tentacles to catch particles in water, sorting them out so that large particles are expelled, small eaten and medium used to build tube
-Other sedentary worms include sand mason and Arenicola (lugworm) that live in burrows and draw in sand to feed on, extracting organic material and defecating in burrow, producing worm casks

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87
Q

Polychaeta reproduction

A

-Mostly dioecious
-Most externally fertilise, some internal
-Spawning may be synchronous (egg and sperm release timed)
-Epitoky occurs
-Larvae form with cilia that swim until suitable habitat is found

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88
Q

Epitoky

A

-Transformations of polychaeta during reproduction
-Includes development of elaborate parapodia for a lot of swimming, or a feeding apparatus so that more energy can be focused on reproduction

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89
Q

Clitellata features

A

-No parapodia
-Produce clitellum (important for reproduction and cocoon production)
-Hermaphrodite
-Gonads restricted to a few segments

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90
Q

Oligochaetes (earthworms) features

A

-Few setae
-Dependent on peristaltic locomotion
-Terrestrial forms burrow and change depth based on moisture
-Recycle soil nutrients, feeding and decomposing organic material
-Also bring leaf material into burrow
-First segment is prostomium, second is mouth
-Male and female gonopore in particular segment
-Clitellum also known as saddle and is hear the head

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91
Q

What did Darwin discover about oligochaetes?

A

-Respond to vibrations
-Material brought into burrow by narrowest part, suggesting intelligence

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92
Q

Mutual sperm transfer in Lumbricus earthworms

A

-Pair up head to tail
-Clitellum produces mucus to stick worms together
-Sperm released from male gonopore travels along sperm grooves, crossing over near head of other worm in the spermathecal opening
-Worms then come apart, and clitellum produces cocoon
-Cocoon wriggles through worm, passing over female gonopore, releasing eggs that go over spermathecal opening (where other worm sperm is)
-Pops off top of head and closes up, developing in cocoon
-Miniature worms released (no larvae stage)

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93
Q

Hirudinean features

A

-No setae
-Restricted number of segments (34) although markings make it appear to be more
-Mutual sperm transfer
-No septa but crawl with suckers (also have jaws for feeding)
-Predaceous

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94
Q

Hirudinean locomotion

A

-Latches on with suckers, followed by waves of contractions
-Can also swim by undulating body

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95
Q

Hirudineans predation

A

-Feed on other small invertebrates
-Use jaws to process prey
-Some suck bodily fluids from animals
-Some use enzymes to break down flesh for blood
-Blood suckers produce anticoagulant (hirudin) and anaesthetic (no scientific evidence for this)
-Can live off meal for six months

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96
Q

Mollusc general structure

A

-Visceral mass (gut and other organs) covered in mantle, which produces shell if present
-Mantle cavity holds gills (for respiration)
-Head/foot region
-Mouth has radula
-Plastic body plan with 7 different groups

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97
Q

Mollusc respiration

A

-Cilia controls water flow
-Blood flowing in opposite directions

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98
Q

Mollusc nervous system

A

-Relatively simple
-Nerve ring around oesophagus and branches into head/foot region and visceral mass

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99
Q

Mollusc radula

A

-Used to graze
-Teeth move around as if on a conveyor belt
-Some modified to drill into shells (dog whelks) or inject

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100
Q

Gastropod developments

A

-Development of head
-Dorso-ventral elongation of body
-Shell (from shield to a protective retreat)
-Torsion
-Some specialised and unique to specific regions such as partula

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101
Q

Development of head in gastropods

A

-More sensory organs such as tentacles or eyes (varying complexity)
-Organs for detecting chemicals and gravity

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102
Q

Torsion in gastropods

A

-Rotation of visceral mass and mantle cavity through 180 degrees
-Mantle cavity goes from back to front
-Advantages are protection of veliger larva (can retreat into mantle cavity), protection of adult and utilisation of oncoming water by gills
-A disadvantage is having the anus over the head

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103
Q

Abalone

A

-Evolution of gastropod meant modifications of mantle cavity to solve salination problem and water flow
-Abalones have little holes in shell for water to enter underneath
-Waste products are taken out through anus

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104
Q

Gastropod shell coiling

A

-Planispiral (symmetrical) sits very high on animal
-Conispiral (assymetrical) is sloped, making it a better shape for movement
-Vast majority of gastropods usually coil on right-hand side, but some coil on left
-Within species, some can be left coiling

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105
Q

Pulmonates

A

-Most specialised gastropods
-Terrestrial
-Mantle cavity is vascularised (rich blood supply) and functions like a lung (no gills)
-Can take in air from an opening

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106
Q

Nudibranchs

A

-Sea slugs
-Undergo detorsion
-No gills, use cerrata on outside surface for respiration
-Rhinophores used for chemical detection
-When disturbed produces inky substance containing opaline, which is found to disrupt shells of crustaceans that prey on it

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107
Q

Partula

A

-Found in Tahiti and Moorea (Pacific islands)
-There was a pest problem on the island (African land snail, so predatory rosy wolfsnail brought in to feed on snails (biological control)
-The rosy wolfsnail did not eat the African land snails, instead eating Partula, reducing populations to near extinction

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108
Q

Bivalve general structure

A

-Shell consists of two parts (hence name)
-Eyes on mantle edge that vary in complexity
-No radula or sensory structures in head region
-Various palps to gather up food and pass to mouth
-Various abductor muscles that open shell for feeding
-Foot used to anchor and gather food
-Foot and gills vary in size
-Reduced nervous system
-Most are lamellibranchs (filter feeders)
-Most dioecious

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109
Q

Bivalve lamellibranchs

A

-Use gills to draw in water
-Filtering system occurs
-Palps also help sort
-Have greatly enlarged gills for this

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110
Q

Examples of bivalves

A

-Mussels
-Giant clams
-Scallops

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111
Q

Mussels

A

-In intertidal zones
-Use bisal threads to anchor
-Also use threads to protect from predators such as dog whelks

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112
Q

Giant clams and algae

A

-Symbiotic relationship
-Clams gain photosynthetic products
-Algae help with the laying down of shell

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113
Q

How do scallops move

A

Able to flap shells

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114
Q

Cephalopods basic structure

A

-Marine carnivores
-Orientation of body has changed, becoming elongated with an anterior/posterior axis
-Shell reduced/lost except in Nautilus and fossils
-Foot modified into tentacles, with various sensory structures
-Do not rely on cilia, but instead muscular contractions bring in water and produce jet propulsions for movement
-Have jaws and radula
-Some produce neurotoxins (such as blue ringed octopus)

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115
Q

Cephalopod nervous system

A

-Well developed
-Cephalisation (concentration of nervous tissue to form brain (biggest in any invertebrate) enclosed in cartilaginous tissue)
-Eyes are very sophisticated and compared to vertebrate eyes but operate slightly different

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116
Q

Cephalopods colour changing

A

-Can change colour due to chromatophores that change shape, directed by relaxing or contracting of muscle cells
-Used for mating displays and to avoid predation
-Octopuses were trained to take different coloured balls, while others watched and copied, showing that they can learn from each other

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117
Q

Cephalopods circulatory system

A

-Closed
-Oxygenated blood pumped into heart and then around body through vessels

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118
Q

Nautiloids

A

-First appeared in the Cambrian
-Found in deep water
-Live in end cavity within shell
-Eye less sophisticated
-Less active and predatory
-Other shell chambers responsible for buoyancy control
-Cephuncle concentrates irons inside, causing water to flow in through osmosis
-If salts move into other chambers, so will water
-Thought that shell evolved from nautilus-like animal

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119
Q

Coleoidea

A

-Cuttlefish, squid, octopi
-Cuttelfish have internal shell (cuttlebone) that aids in buoyancy
-Squid have shell reduced to proteinaceous pen that runs through animal to give support, with buoyancy instead controlled using ammonia
-Octopi shell vestigial/absent and are typically benthic, with an extremely flexible body shape

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120
Q

Arthropod groups

A

-Arachnids
-Crustaceans
-Myriapods
-Insects

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121
Q

Mites

A

-Free-living and parasitic
-Dustmites produce harmful halogens
-Varroa feed on haemolymph of larvae stages of bees, transferring virus such as deformed wing virus and can collapse hive systems of honeybees
-Both ticks and mites have chelicerae and pedipalps

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122
Q

Ticks

A

-Ectoparasites
-Have hypostome
-Small but expand when take up blood
-Some transmit diseases such as Lyme disease, named after town where it was first described and transmitted by spirochete

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123
Q

Crustacean general structure

A

-Predominantly aquatic (terrestrial forms include woodlice)
-Two pairs of antennae
-A lot of variation due to tagmatisation and adaptive radiation of appendages
-Mandibles and first and second maxilla
-Biramous appendages
-Some carry females precopula, waiting for moulting, as the cuticle will be soft enough to penetrate
-Nauplius larva

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124
Q

Crustacean variation in appendages example

A

Crayfish have a combined head and thorax, with walking legs in thorax, one modified as a claw and tiny appendages used for swimming in the abdomen

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125
Q

Crustacean respiration

A

-Through internalised gills in branchial chamber
-Originated from thoracic appendages (epipods)
-Terrestrial epipods modified to contain tubes instead

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126
Q

Biramous appendages in crustaceans

A

-Two branched
-Can be different structures for swimming and walking
-Endo and exopods

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127
Q

Modifications in Daphnea (waterflea)

A

-Small abdomen fused with thorax
-Thoracic appendages for food collection and current generation (for respiration)
-Surrounded by carapace
-Second antennae for swimming
-Undergo sexual reproduction if conditions are harsh, but usually asexually produce identical females

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128
Q

Modifications in barnacles (e.g. Balanus)

A

-No abdomen
-Live in shell
-Extend thoracic appendages when tide is low to collect food and pass to mouth
-Close valves when tide is gone
-Mostly hermaphrodite
-Largest penis to body ratio in animal kingdom to broadcast sperm far
-Used to be thought to be molluscs
-Goose barnacles get name because used to be thought to be baby geese
-Can be parasitic

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129
Q

Parasitic barnacles

A

-Sacculina
-Attack and penetrate crabs, castrating males
-Changes infected crab behaviour, feminising males
-Crab ‘wafts’ baby parasites away, as a female crab would do to offspring

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130
Q

Fiddler crabs

A

-Massive claws
-Found that females found males with biggest and fastest moving claw the most attractive
-Males tolerate inferior males to hang around burrow to make self-esteem more attractive
-Lure females into burrows

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131
Q

Myriapods

A

-Centipedes
-Millipedes
-Tracheal system, branching tubules with access to outside
-Move air through diffusion and muscular contractions
-Malphigian tubules remove substances from haemolymph

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132
Q

Centipede basic structure

A

-Don’t all actually have 100s of legs, some known to have up to 300
-Dorsal-ventrally flattened
-Mandibles for processing food
-First thoracic appendage modified to form a poison claw
-Predacious
-Vary in size
-Usually simple eyes but can have complex structures

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133
Q

Millipedes

A

-Detritovores, feed on leaf material
-More spherical
-Like centipede, not well adapted to land so live in damp soils
-‘1000s of legs’ but most is 750
-Get name as every two segments are fused together, with 4 appendages on each segment, giving impression of lots of legs
-Important for recycling nutrients within soil
-Vulnerable due to no protective claws, so produce deterrents such as hydrogen cyanide, produced from repugnatorial glands
-Some animals exploit millipede chemicals, irritating millipedes and using their toxins as an insecticide against mosquitos etc (can also get high)

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134
Q

Hemichordate features

A

-Coelomates (deuterostomes)
-‘Half chordates’ as thought to have similarities to chordates, but not fully chordates
-Examples include enteropneusts (acorn worms) and pterobranchs (sea angels)

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135
Q

Chordate features

A

-Notochord
-Dorsal, hollow nerve cord at top
-Pharyngeal (gill) slits
-Post-anal tail
-Endostyle

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136
Q

Notochord

A

-Like a rod coated in a fibrous sheet
-Provides form of support
-Can form a base for muscular contractions

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137
Q

Pharyngeal slits

A

-Found in pharynx (first part of digestive system)
-Used for feeding in invertebrates
-Vertebrates that retain these (not humans) use these for respiration

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138
Q

Endostyle

A

-Found in invertebrates
-Concentrates iodine and provides music (????)
-Homologous as thyroid

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139
Q

Enteropneusts

A

-Delicate
-Found buried in mud
-Distinctive structures (proboscis, collar and trunk)
-Vary in size and can be deep-sea or shallow-sea
-Use proboscis to collect food
-Gill slits used for respiration
-Has stomochord to support heart and excretory syst
-Larval stage (tornaria) is similar to echinoderm
-Nerve net (no dorsal hollow nerve cord)

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140
Q

Nerve net in enteropneusts

A

-Some concentration of nervous tissue in collar region
-More complicated
-Hollow

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141
Q

Pterobranchs

A

-Few mm long
-Sessile, live in colonies
-Proboscis, collar and trunk
-Lophophore used for food collection
-Some have gill slits
-Simple nerve net
-Stomochord supports oral shield
-Covered in tunic
-Can be traced back to graptolites (Cambrian-Devonian)

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142
Q

Nervous system of pterobranchs

A

-Diffused nerve net
-Not well studied so could be hollow

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143
Q

Hemichordates resemblance to chordates?

A

-No notochord
-No tail
-Nervous tissue can be hollow but not dorsal nerve cord
-Collect food externally
-BUT do have gills (pax gene expression in pharynx is the same)

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144
Q

Hemichordates resemblance to echinoderms?

A

-Similar larval stages
-Similar nervous systems (but acorn worm expresses genes in same order as chordates)
-Gill slits (homolazoans) present in ancient echinoderms

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145
Q

Chordates

A

-Vertebrates
-Phylogeny shows similarities with other deuterostomes BUT with dorsoventral axis inversion (completely upside down compared to other animals, even genes produced)

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146
Q

Invertebrate chordates

A

-Urochordates (tunicates)
-Cephalochordates (lancelets - amphioxus)

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147
Q

Urochordates

A

-Covered in tunic
-Have a ‘tadpole’ larval stage
-Sometimes called sea squirt, as water is released from siphons
-Most common group are ascidians
-Deep sea carnivorous tunicates siphons are modified to form traps

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148
Q

Examples of tunicates

A

-Botryllus sp (star tunicate)
-Colonial sea squirts with larger bodies and siphons
-Salps are solitary and non-sessile, and swim to bottom of sea during day to avoid predation
-Larvacea/appendicularia stay in ‘larval’ stage for whole life
-Deep sea carnivorous tunicates siphons are modified to form traps

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149
Q

‘Tadpole’ larval stage in tunicates

A

-All chordate features found
-During metamorphis, features are lost or reduced (except pharyngeal gill slits)
-Has papilla at anterior end
-Settles on anterior end and enters rapid growth

150
Q

Cephalochordates

A

-Limited species with limited variation
-Spend most of adult time buried in sand or mud, leaving to reproduce and release gametes
-Filter feed in sand and mud
-Has all chordate features in adult life
-Endostyle produces mucus
-Water flows through atriopore
-Notochord runs all the way to head
-Pigment spots as ‘eyes’ to detect light
-Cilia

151
Q

Cilia of cephalochordates

A

-Run along pharyngeal slits and surrounded in a chamber
-Generates current that passes water to mouth, where large items are prevented from entering

152
Q

Brief structure of ocean

A

-71% of Earth’s surface
-Every major phylum of invertebrates has some marine representatives
-Neritic zone includes land, oceanic zone has none
-Eulittoral/intertidal zone
-Continental shelf
-Continental slope
-Abyssal plane
-Mariana trench

153
Q

Photic zone

A

-Light can reach as far as 200m
-Photosynthesis can occur
-Includes intertidal zone and continental shelf

154
Q

Eulittoral/intertidal zone

A

-In neritic zone
-Range between lowest and highest tide points
-Animals here are covered and exposed each day
-Variation in tides throughout year
-Not great conditions, animals are adapted

155
Q

Tidal variation

A

-Spring tides go out the furthest and go highest up the beach
-Neap tides are the opposite, having less tidal range

156
Q

Animal adaptations to intertidal zone

A

-Barnacles close up ‘valves’ to contain moisture when tide is out and open to eat when the tide comes in
-Sea anemones retract tentacles when tide is out and has them out for food when tide is in
-Winkles hide away in crevices and damp regions

157
Q

Continental shelf

A

-Down to 150-200m
-Still neritic zone, as water with land below
-Tropical areas have coral reefs

158
Q

Coral reefs

A

-0.1% of ocean’s area, home to 25% of marine species
-Made of polyps and calcium carbonate, and symbiotic relationship with algae that help deposit the calcium carbonate

159
Q

Continental slope

A

-Down to about 3000m
-Here onwards is oceanic zone

160
Q

Abyssal plain

A

-3000-5000
-Vast
-Not much known about it

161
Q

Adaptations of animals to live in the aphotic zone as no phytoplankton

A

-‘Marine snow’, debris from the top waters
-Sponges usually filter feeders, but the harp sponge of the aphotic zone is predatory
-Squids usually predatory, but the vampire squid is a deposit feeder, gathers up marine snow by wafting retractable tentacles that plankton etc get stuck to

162
Q

Other features of vampire squid

A

-Has protective spines inside and can turn itself inside out when threatened to reveal them
-Believed to be more related to octopus than squid, but has differences with both

163
Q

Mariana trench

A

-Deepest part of ocean, down to 11000m (Everest is only 9000m)
-First explored in 1960, but nothing seen due to silt
-Not explored again until 2012
-Food availability scarce due to harsh conditions

164
Q

An animal adapted to finding food in the Mariana trench

A

-Hirondella gigas
-Found in Challenger Deep (deepest part)
-Amphipod (shrimp)
-Large considering harsh environment
-Found to containing cellulase (cellulose breakdown enzyme)
-Normally, at high pressures, proteins and enzymes don’t function properly, however cellulase does
-Hirondella gigas feeds on plant material and wood

165
Q

Deep sea hydrothermal vents

A

-‘Mountains underwater’, mid-ocean ridges that form areas of high activity, forming hydrothermal vents
-Spew out chemicals
-Another form of food as they provide an input of nutrients into the deep sea

166
Q

Freshwater environment

A

-Less constant than seawater
-Gametes, eggs and developing young need protection
-Waste can still be expelled as ammonia
-Support still provided

167
Q

How is freshwater less constant than the sea and why is it bad?

A

-Temperature and oxygen variability
-Osmotic regulation needed
-Turbidity, velocity and volume (freezing and drying) can change

168
Q

Temperature and oxygen variability in freshwater

A

-Winter temperature is relatively constant with depth, as is oxygen
-Summer temperatures and oxygen decrease with depth
-As water reaches 4C, during seasonal changes when water changes temperatures, it becomes more dense and sinks, and is replaced with hotter water

169
Q

Fertilisation and development in the sea

A

-External fertilisation can occur
-Currents help move gametes and larva
-No complex osmoregulation needed in larval stages

170
Q

How are deep ocean currents formed?

A

Seawater becoming colder and thus dense, sinking and drifting to form slow currents

171
Q

Reproduction and development in freshwater environments

A

-Gametes, eggs and developing young need protection
-Eggs retained by parent or attached to bottom of stream to keep in place
-Or development is direct (no larval stage)

172
Q

Why are estuarine environments productive?

A

-Runoff of nutrients
-Organisms that live there must be tolerant of harsh conditions, so there is less competition

173
Q

Seasonal variations in estuarine environments

A

-Rivers can change in flow, effecting the salinity of the estuary
-Rivers could also dry up

174
Q

What organisms could habit estuarine environments?

A

-Freshwater organisms adapted to small salinity levels
-Seawater organisms adapted to less salinity

175
Q

Effect of mode existence

A

-Free-moving organisms are bilaterally symmetrical (can be cut in one way) and show cephalisation (concentration of nervous tissue with sensory information at one end (usually anterior))
-Attached/sedentary organisms are radially symmetrical and adapted to limited movement

176
Q

General structure of protozoans

A

-Single-celled
-Eukaryotic
-Motile
-Heterotrophic (cannot produce own food)
-Complex
-Pellicle
-Some have a test
-Contractile vacuole

177
Q

Pseudopodia

A

-Temporary extensions of the body due to changes in internal pressure of organism
-Ectoplasm loses rigidity, allowing endoplasm to flow into that point, moving the organism in that direction
-‘False feet’
-Lobopodium are blunt structures formed, and filopodium are pointy

178
Q

Digestion in protozoans

A

-Food broken up by enzymes in cytoplasm
-Products dispersed from vacuole in tiny vesicles to increase SA for absorption of the substances into cytoplasm
-Waste products ejected from cell via vesicles
-Some use a cytoproct as specific spot to remove waste

179
Q

Entamoeba dispar and colis

A

-Commensals
-Don’t really effect host (can in high numbers)
-Feed on bacteria

180
Q

Entamoeba histolytica

A

-Pathogen
-Infected cysts enter humans through food and water, usually faecal contamination
-End up in large intestine, using histolytic enzymes to digest human cells of intestine wall, causing ulcers and abscesses
-Can enter bloodstream to liver, lung, brain etc
->55,00 deaths/yr

181
Q

Asexual haploid cycle of protozoans

A

-Spend entire time as haploid
-Undergo binary fission repeatedly

182
Q

Haploid adults with zygotic meiosis in protozoans

A

-Produces isogametes
-Isogametes join to form a diploid zygote
-Then meiosis to form haploid cell

183
Q

Diploid cycle of protozoans

A

-Diploid for most of life
-Produces haploid gametes via meiosis

184
Q

Haplodiploid cycle

A

-Alternation of generations
-Diploids undergo meiosis to form haploid spores
-Haploid grow up and produce haploid gametes
-Haploid gametes join to form diploid zygote
-Also seen in plants

185
Q

Endosymbiont theory of origin of protozoans

A

-Ancestral prokaryotic organism engulfed other organisms
-Instead of digesting, it utilized features of organisms such as aerobic respiration

186
Q

Methods of prevention for malaria

A

-GM mosquitos, making male testes fluoresce so that they can be noticed, sterilised, and released to cause a population crash
-Editing ‘doublesex’ gene, giving females both male and female reproductive organs, rendering them unable to reproduce
-Artemisinin from sweet wormwood

187
Q

Animal and vegetal pole

A

-Animal pole is at the top of the egg
-Vegetal pole is at the bottom

188
Q

What part of the egg effects development heavily?

A

-Amount of yolk
-Can be isolecithal, with evenly distributed yolk
-Can be telolecithal, with yolk concentrated at one end
-Can be centrolecithal, with yolk concentrated at middle

189
Q

Main steps of fertilisation

A

-Egg and sperm join to form a zygote
-Egg is also activated, leading to embryonic development
-Replication and first division
-Acrosomal and cortical reactions

190
Q

What animal is used as a model for looking at invertebrate development?

A

Sea urchin, a benthic echinoderm that undergoes external fertilisation

191
Q

Acrosomal reaction (in sea urchin)

A

-Sperm heads contain actin pool and acrosomal vesicle
-Sperm makes contact with jelly coat of egg and discharges hydrolytic enzymes from acrosomal vesicle that start digesting jelly coat
-Actin pool begins to polymerise, extending to form an acrosomal process
-On surface of acrosomal process is a protein called bindin that connects to receptors on the vitelline layer of the egg (species specific), latching on
-Acrosomal process makes its way through vitelline layer, eventually touching the egg plasma membrane
-The plasma membranes fuse and sperm nuclei is dragged into cell cytoplasm
-Connecting of egg plasma membrane and acrosomal process triggers a series of reactions

192
Q

What is triggered by the connecting of egg plasma membrane and acrosomal process?

A

-Egg plasma membrane loses charge, causing sodium ions to flow into egg
-Potential of egg plasma is now positive, repelling the other positively charged sperm
-Fast block to polyspermy
-Also triggers cortical reaction and activation of egg

193
Q

Cortical reaction

A

-Change in membrane potential causes calcium to be released within cytoplasm
-This stimulates fusion of cortical granules with plasma membrane
-Cortical granules contain enzymes that break down fusion between egg plasma membrane and vitelline
-Also solutes in cortical granules, allowing water to enter through osmosis, causing a swell
-Vitelline layer polymerised by polymerizing enzymes from cortical granules, to become fertilisation membrane
-Slow block to polyspermy

194
Q

Activation of egg

A

-Change in potential of egg plasma membrane stimulates metabolic changes
-This includes protein synthesis and oxygen uptake
-pH also changes from 6.8 to 7.3

195
Q

Urchin fertilisation times

A

-Sperm and egg merging takes 20 minutes
-Replication and first division takes 90 minutes

196
Q

Three main stages of embryonic development

A

-Cleavage
-Gastrulation/morphogenesis
-Organogenesis

197
Q

Cleavage

A

-Division of embryo into more cells
-Rapid division to form a ball of cells (blastomeres)
-Affected by yolk
-Can be radial or spiral
-Eventually, a solid ball of cells is formed, known as a morula
-This then becomes a blastula with a space inside called a blastocoel

198
Q

Effects of yolk on cleavage

A

-Isolethical leads to a holoblastic complete cleavage (can divide properly) and yolk is evenly distributed
-Slightly telolecithal leads to unequal holoblastic cleavage as some blastomeres are smaller than those with yolk
-Strongly telolecithal leads to meroblastic incomplete cleavage
-Centrolecithal leads to a superficial cleavage
-Different amounts of yolk lead to differently shaped blastulas

199
Q

Radial cleavage

A

-Shown by sea urchin
-First two divisions are polar
-Next cleavage is at either parallel or perpendicular plane
-Looking from top, top cells sit directly on bottom cells
-Indeterminate cleavage, the fate of the cells is not determined this early in development, and can become different things

200
Q

Spiral cleavage

A

-First two divisions polar
-Next plane is diagonal to the vertical
-Top cells sit on groove of bottom cells
-Determinate cleavage, fate is fixed

201
Q

Gastrulation

A

-Also affected by yolk amount
-Converts blastula to gastrula by buckling in to form a new region, the archenteron (embryonic gut)
-A single row of cells has now become two layers
-Entrance is a blastopore and either becomes mouth or anus, depending on animal group, and a second opening is eventually made for the other

202
Q

Layers of the gastrula

A

-Cells around outside of embryo are the ectoderm
-Cells within embryo are the endoderm, lining the embryonic gut
-The space between, in most animals, is the mesoderm
-There are now 3 body layers, making it tripoblastic, as most animals are
-Body layers also called primary germ layers, as they give rise to organs and tissues in future

203
Q

Non-tripoblastic animals

A

-Sponges don’t really have tissues
-Cnidarians have two body layers
-Some vertebrates thought to have 4 layers

204
Q

Formation of mesoderm

A

-Can be formed from a mesentoblast, a series of cells that eventually become the mesoderm through proliferation
-Can also be formed by outpocketing of the archenteron

205
Q

How does the blastula ‘buckle in’ to form archenteron?

A

-Cells in vegetal pole lose their cohesiveness
-In sea urchins, some cells have filipodia (like small flagella) and use them to grip onto the endoderm and pull it further in

206
Q

What does the sea urchin blastopore become?

A

Anus

207
Q

What do the body layers become?

A

-Ectoderm becomes outer covering and nervous system
-Endoderm becomes gut and associated structures
-Mesoderm becomes muscles, body cavity if has one (coelom), circulatory system, most internal support structures

208
Q

Arrangements of body layers

A

-Different animal groups have different arrangements of layers, and it used to be a way of classifying but is now shown not to mean a relation
-Acoelomate
-Pseudocoelomate
-Coelomate

209
Q

Acoelomate

A

-Lacks body cavity between gut and outer body
-Gut surrounded by endoderm
-Outside body surrounded by ectoderm
-Between them is only a solid mass of mesoderm

210
Q

Pseudocoelomate

A

-Body cavity only partially lined by mesoderm
-Mesoderm forms muscle layer
-Body cavity lies between endoderm and mesoderm
-Cavity (pseudocoelom) only lined by mesoderm on one side
-Generates a lot of pressure due to muscle layer pushing on only one side

211
Q

Coelomate

A

-True body cavity
-Body cavity completely lined by mesoderm (inside and outside)
-Coelom can be used as a transport system, for storage or for a skeleton

212
Q

Two evolutionary lines of tripoblastic animals

A

-Protostomes show spiral and determinate cleavage, are schizocoelous (mesoderm (and coelom) come from proliferation of mesentoblast) and mouth develops from blastopore (second hole is mouth), as protostome means ‘first mouth’
-Deuterostomes show radial and indeterminate cleavage, are enterocoelous (mesoderm formed by outpocketing) and anus develops from blastopore

213
Q

Life histories affected by amount of yolk

A

-Planktotrophic indirect
-Lecithotrophic indirect
-Planktotrophic direct

214
Q

Planktotrophic indirect

A

-Weakly isolecithal ova, lost of them
-Free spawning, important to disperse widely
-Free swimming, planktotrophic (plankton-like) larvae form
-Followed by settlement and metamorphosis
-Due to less yolk, rely a lot on feeding during larvae stage
-Common in marine invertebrates in intertidal zone
-Unpredictable success

215
Q

Lecithotrophic indirect

A

-Moderately to strongly telolecithal, not many
-Free spawning, important to disperse widely
-Free swimming, lecithotrophic larvae
-More yolk, so less reliant on feeding
-Found in more benthic marine environments where food availability is low
-Larvae settle and metamorphose

216
Q

Metamorphis and settlement of lecithotrophic and planktotrophic indirect larvae

A

-Metamorphosis is hardest part
-Before settling, larvae assess chemical and physical features of the environment to find best place
-Some even settle and then move later

217
Q

Planktotrophic direct

A

-Strongly telolecithal ova, few of them
-Requires internal fertilisation
-Requires brooding or encapsulating of embryos
-No larval stage, hatch as juveniles
-Seen in terrestrial and freshwater environments

218
Q

Brooding or encapsulating of embryos in planktotrophic direct animals

A

-Oviparous animals lay eggs
-Ovoviviparous brood or retain eggs, with developing embryos receiving nutrients from egg yolk only
-Viviparous retain embryos inside, where they receive nutrients from mother

219
Q

Animals divided on basis of symmetry

A

-Radiata are radial and sessile/sedentary e.g. Cnidarians
-Bilateria are bilateral and active

219
Q

Animals divided on basis of symmetry

A

-Radiata are radial and sessile/sedentary e.g. Cnidarians
-Bilateria are bilateral and active
-Echinoderms are radially symmetrical despite being bilateria as this sustains their lifestyle

220
Q

Protonephridia

A

-Excretory tube that lacks an internal opening
-Contain excretory canals
-Also have bulbs containing flagella
-Flagella waft, creating current, drawing in waste to be expelled

221
Q

Xenacoelomorpha

A

-Basil bilaterians??
-Or maybe more complicated??
-Once thought to be platyhelminthes, now not

222
Q

How do insects differ from other arthropods?

A

-Body is divided into three regions (tagmata)
-Usually have 6 legs at some point in life
-Head bears one pair of antennae
-In most adults, thorax bears 2 pairs of wings, in fact all winged invertebrates are insects

223
Q

Insect tagmata

A

-Specialised groupings of repetitive body segments
-Head (ca. 4-6 segments, evolutionarily integrated for feeding, sensation etc)
-Thorax
-Abdomen

224
Q

Insect head features

A

-Mandibles
-Maxillae
-Maxillipeds
-Antennae
-Labrum

225
Q

Why are insects important?

A

-Furnish biology with model systems, such as Drosophila melanogaster
-Affect people in many ways
-1M described species (between 2-30M undescribed, 80% of all species)
-Diversity is not reflected in natural history books
-Play a major role in ecosystems

226
Q

Negative effects insects have on people

A

-600M people are affected by diseases
-These diseases also affect livestock, such as the sheep strike fly
-Insects attack crops (15% lost worldwide), stored products (grain) and timber (housing)

227
Q

Sheep strike fly

A

-Larvae feed on dead tissue of sheep
-Sheep rub against trees, cutting skin
-Flies enter wound and lay eggs
-Larvae hatch and eat flesh, which is very painful for the sheep

228
Q

Insect benefits to humans

A

-70% of flowering crops require insect pollination
-Insects are often major biocontrol agents

229
Q

Major role of insects in ecosystems

A

-Ants are the predominant animal biomass in tropical forests
-5-20% of the Earth’s plant biomass is consumed annually by insects, making them a conduit for passing carbon up the trophic levels
-Insects are a major driving force behind nutrient cycling, sustaining ecosystem communities and crop yields

230
Q

Fossil evidence for insects

A

-Most abundant fossil insects are Palaeodictyoptera (found in the Carboniferous)
-Only modern groups at same time were Ephemeroptera (mayflies) and Odonata (dragonflies)
-Oldest fossil insects are from Devonian and are Collembola (springtails), litter dwelling insects

231
Q

Palaeodictyoptera structure

A

-Typically the thorax bears two pairs of wings that are loose, unflexing and poorly coordinated (contrasting to modern insect wings)
-Long tails
-Undifferentiated mouth parts that suggest plant diet
-Probably gliders, not fliers
-Distinct head with antennae and compound eyes
-Elongated 11-segmented abdomen and cerci (likely for balance)

232
Q

Two hypotheses for origin of Arthropods (and insects)

A

-Was believed arthropods (and insects) are multiply derived from different worm ancestors due to the shared segmentation patterns (polyphyly)
-Second proposition was that insects and arthropods have a single origin and insects were initially biramous (monophyly)

233
Q

Polyphyly theory of origin for arthropods

A

-Sidnie Manton, a comparative anatomist, believed that similarities in the arthropods were due to constraints imposed by a rigid exoskeleton
-Manton evaluated the limbs of arthropods, noticing that those of insects and myriapods were uniramous as opposed to biramous limbs of other arthropods
-This led her to place them closer together on phylogeny, and was proposed that insects were always uniramous, even in ancestral form
-However if there were multiple ancestors, certain traits associated with shift to land would have had to evolutionarily converge

234
Q

Traits associated with shifting to land of insects

A

-Malpighian tubules
-Tracheal system
-Loss of secondary antennae

235
Q

Monophyly theory of origin for arthropods

A

-Shared derived characteristics used to create phylogenetic tree
-Suggests closer relationships between insects and crustaceans than myriapods

236
Q

Which hypothesis for arthropod origin is true and what is the evidence?

A

-Modern insects are clearly uniramous, and if legs were never branched then polyphyly theory is correct
-Neuroanatomy shows that brain and visual system of insects is very similar to crustacea, and very dissimilar to worms
-Developmental genetics shows that distal-less determines limb branching, with both insects and crustacea having this gene, but its regulated differently
-Analysis of 41K bp of genomic DNA sequence of 62 nuclear genes shows that arthropods do form a monophyletic group, and that insects are essentially crustaceans that invaded land

237
Q

So from what and when did insects evolve?

A

-Evidence shows that insects arose from a crustacean-like ancestor (not a worm), invading land about 500Mya
-This animal had to solve a lot of physical and physiological problems

238
Q

What challenges were faced moving from aquatic to marine environments?

A

-Water loss (and osmoregulation) due to small size
-Respiring in air
-Reproduction and fertilisation
-Support and movement

239
Q

What helped insects with the transition between aquatic and terrestrial environments?

A

-Thought that transition happened slowly, and likely involved a bridging habitat, such as estuaries, marshes, the intertidal zone and mangroves
-Each provided a gradation of chemical and physical environments from both marine and terrestrial, giving the animal a step to becoming adapted to fully terrestrial environments
-We find examples of bridging species today

240
Q

How did insects solve water loss challenges when transitioning to land?

A

-Probably solved by evolution of cuticle (epicuticle), that sets them apart from other crustacea and is a waxy layer on top of insect integument, allowing the regulation of water loss
-Epicuticle is a living structure, shown by pores and wax production sections constantly replacing wax surface
-Probably initially evolved to prevent entrapment in water film
-Insect integument (outer layer) has many similarities with crustacean exoskeleton, but also some differences
-Electrolyte homeostasis solved with the Malpighian tubules

241
Q

Similarities between insect integument and the crustacean exoskeleton

A

-Is chitin based (set of glucosamine polymers that have crosslinks with protein, with the crosslinks causing sclerotization, forming the hardness of the integument, and different parts contain different levels of sclerotization (more in the harder mandibles))
-Flexible, meaning it can have a lot of different adaptations to allow different functions e.g., invagination of cuticle to form internal anchor-points for muscles, or evaginations to form protective features such as spines or hooks
-Apodemes and ultrastructure as adaptable support

242
Q

Differences between insect integument and crustacean exoskeleton

A

-No calcite in tegument, meaning no biomineralization
-More extensive protein-x links with chitin to compensate lack of calcite
-Waxy epicuticle on top of integument, an important adaptation allowing regulation of water loss

243
Q

Biomineralization

A

-Incorporation of minerals into the exoskeleton of crustaceans to provide, for example, the hard carapace of crabs)

244
Q

Malphigian tubules

A

-Insect ‘kidney’ but not actual kidney as no flow through
-Blind tubules lead from abdomen into gut cavity, providing mechanism for water retention, and some selective ion retention
-‘Urine’ produced is referred to as a non-selective ion retention produced in Malphigian tubules and deposited in the hindgut, where there is additional water retention, and ejected with faecal matter
-Less developed or absent in early terrestrial insects

245
Q

How did insects solve the problem of respiring in air when moving to land

A

-Mystery
-Insects have a unique system, the trachea

246
Q

Insect trachea

A

-Network of gas exchange spiracles, tubules, tracheoles, representing invaginations of the cuticle, with internal sacs for gas exchange
-Ventilation can be through tidal flow through all spiracles or can be regulated
-Air flow is through external pores to enter the tubes, and as oxygen is consumed, the pressure gradient within tubules drops, facilitating tidal flow of air through spiracles
-External structures (spiracles) have capacity to open or close under muscular control (probably to optimise amount of gas exchange per unit of water loss) but air flow is typically passive

247
Q

Insect trachea variation

A

-If insect is highly active, it will require more extensive selection of trachea to support rapid gas exchange
-Aquatic insects, such as mosquito larvae or diving beetles, have had to come up with workarounds for the tracheal system, like beetles carrying an airbubble underwater

248
Q

What do the tracheal tubules have a similar structure to?

A

Insect integument

249
Q

What modern-day bridging insect species do we see?

A

-Remipedia found in anchialine pools next to the sea
-May resemble an intermediate form
-Habitat is not good for fossils so no hard evidence

250
Q

How did insects adapt their ways of reproduction and fertilisation due terrestrial environments?

A

-In water reproduction is easy, and can be done by egg and sperm deposition
-All internal fertilisation on land
-Not all copulate

251
Q

What did insects have to change about their support and movement?

A

-Needed mechanism to support organs and movement
-Gravity in terrestrial environments selects for a smaller size
-Insects have a very stable gait

252
Q

What also helped insects succeed in terrestrial environments?

A

Being the first animals to colonise land (same time as plants) was important for their success

253
Q

Synapomorphy

A

-Character shared by all the descendant species
-Strong evidence for relatedness

254
Q

Synapomorphy of insects

A

-Pattern of tagmosis with a 6-segmented head, 3-segmented thorax and an 11-segmented abdomen
-Reduction in leg segments (fusion of patella and tibia)
-Two primary pigment cells of the ommatidia
-9+9+2 pattern of microtubules in sperm flagellum

255
Q

Entognatha

A

-Includes Protura, Collembola and Diplura
-Mouthparts enclosed by folds
-Less developed Malpighian tubules
-Reduced or absent compound eyes
-Elongated, sac like ovarioles
-Virtually all have eversible vesicles of some kind

256
Q

Major basal lineage insect orders

A

-Collembola (springtails)
-Diplura (bristletails)
-Zygentoma (silverfish)
-Protura

257
Q

Collembola (springtail) features

A

-Important for soil health
-Collophore sac which can be turned out of insect
-Prominent antennae
-Furculum (forked abdominal ‘spring tail’ folded under)
-Compound eyes present but reduced

258
Q

How are springtails important for soil health?

A

-Live in leaf litter and topsoil
-Carbon retention and Nitrogen mineralisation in soil

259
Q

Collophore sac in springtails

A

-For electrolyte balance, water uptake, and adhering to surfaces
-Can help turn body over when stuck on back (self-righting)

260
Q

Diplura (bristletails)

A

-Simple ocelli (no compound eye)
-Antennae present
-Still wingless
-Two prominent cerci

261
Q

Protura

A

-Antennae absent
-Eyes absent
-Elongated body

262
Q

Apterygota vs pterygota

A

-Apterygota are wingless
-Pterygota have wings

263
Q

Apterygota insects

A

-Major basal lineage insects all wingless
-Had chewing mouthparts and probably lived on plant material
-Diverse communities were everywhere and for 60M years nothing much changed
-Then came 3 key innovations in a VERY short space of time

264
Q

What other insect innovations arose?

A

-Wings
-The egg
-Methods of development

265
Q

Early winged insects can be split into two division

A

-Paleoptera
-Neoptera

266
Q

Paleoptera

A

-Basal lineages
-Unable to fold wings back over the body
-No olfactory bulb in brain
-Includes Ephemeroptera (mayflies) and Odonata (dragonflies and damselflies)

267
Q

Ephemeroptera

A

-Mayflies
-Form mass clouds of adults
-2500 species
-Aquatic, with elaborate abdominal gills
-Greatly reduced hindwings
-Long cerci
-Emergence tightly synchronised with environment

268
Q

Odonata

A

-Dragonflies (Epiprocta) and Damselflies (Zygoptera)
-Voracious predators
-Can reach out with jaws
-Water taken into rectum in larvae of dragonflies
-Terminal gills in damselfly larvae
-Compound eyes
-Complex copulation system

269
Q

Compound eyes of insects

A

-Individual units known as ommatidia
-All have lenses, pigments and cones
-Most insects see blue green and UV
-Individual nerves of each ommatidia leading directly to brain
-Relatively decent resolution of sight (1 degree in insects, 0.5 in humans)

270
Q

Complex copulation systems of Odonata

A

-Male transfers sperm to second genitalia
-Grips head of female with abdominal claspers, uses aedeagus to transfer sperm
-Stays with female to mate guard until oviposition occurs

271
Q

Aedeagus

A

-Male pterygota have an aedeagus derived from paired appendages on the 9th segment of abdomen
-Some have structures to scrape out sperm

272
Q

Types of insect development

A

-Ametabolous
-Hemimetabolous
-Holometabolous

273
Q

Ametabolous

A

-Progressive moulting from hatching
-Gradual change
-Only relevant for apterygote insects

274
Q

Hemimetabolous

A

-E.g., grasshoppers
-Distinct nymph and adult form but no radical transformation
-Incomplete metamorphosis
-If aquatic, nymphs are called naiads

275
Q

Holometabolous development

A

-Such as caterpillars
-Non-feeding stage called a pupa between immature larva and adult
-Adult structures develop as imaginal discs inside larvae

276
Q

Insect development nomenclature

A

-Nymphs have several instars before imago
-Insects can have between 4 and 30+ instars (mayflies)

277
Q

Basal Neoptera

A

-Hemimetabolous
-Ability to fold wings
-Monophyletic indirect flight muscles

277
Q

Basal Neoptera

A

-Hemimetabolous
-Ability to fold wings
-Monophyletic indirect flight muscles
-Plecoptera (stoneflies)
-Phasmotodea (stick insects)
-Orthoptera (grasshoppers and crickets)
-Mantodea (mantises)
-Blattodea (cockroaches)
-Isoptera (termites)

278
Q

Hemimetabolous Neoptera

A

-Plecoptera (stoneflies)
-Phasmotodea (stick insects)
-Orthoptera (grasshoppers and crickets)
-Mantodea (mantises)
-Blattodea (cockroaches)
-Isoptera (termites)
-Hemimetabola

279
Q

Plecoptera

A

-Stoneflies
-Reduced ovipositor (eggs dropped into the water in flight)
-Pulsatile organ (accessory heart) associated with the cerci
-3-segmented tarsi
-High O2 requirement

280
Q

Phasmotodea

A

-Stick insects
-All herbivorous
-Pair of defensive glands inside prothorax
-Fusion of thorax with 1st abdominal segment
-Claspers (vomer) present on males for during mating
-Amazing crypsis associated with host plant speciation

281
Q

Orthoptera

A

-Grasshoppers and crickets
-Cryptopleuron, a lateral extension of the pronotum
-Saltorial hindlegs
-Wings inclined over abdomen at rest
-Suborders Ensifera (crickets) and Caelifera (grasshoppers)

282
Q

Ensifera

A

-Crickets
-Fine antennae, >30 segments
-Biting/shearing mandibles
-Auditory organs on legs (protibia)

283
Q

Gryllotalipidae (mole cricket)

A

-Fossorial front legs (for digging), heavily sclerotized
-Unique mating call using shape of a dug pit as a resonating device
-Highly aggressive at high densities

284
Q

Caelifera

A

-Grasshoppers
-Short, robust antennae, < 30 segments
-Chewing mandibles
-Abdominal auditory organs
-A major grasshopper family is Acrididae

285
Q

Acrididae

A

-Major grasshopper family
-Ca. 10,000 sp
-Phenotypes change based on whether solitary or gregarious (social)
-When in swarm, legs bump together with others, causing changes in the brain
-During development (as solitary nymphs), increased density leads to______
-40-80 billion locusts in a swarm, covering millions of hectares

286
Q

Mantodea

A

-Mantises
-Effective predators
-Sophisticated sense apparatuses
-Ambush predation only evolved once

287
Q

Themes in mantodes evolutions

A

-Elongation of thorax
-Development of a cyclopean metasternal ear
-Exquisite camouflage and mimicry, facilitating prey capture, e.g., orchid mantises (Hymenopus coronatus)

288
Q

Mantis synapomorphies

A

-Enlarged, raptorial forelegs
-Femoral brush on front leg
-Extraordinary head mobility
-Ootheca (egg mass) embedded in protective froth

289
Q

Blattodea

A

-Cockroaches
-Wrap-around eyes
-Dorsoventral flattening (for scurrying under leaves in habitat)
-Slightly hardened, leathery (coriaceous) front wings
-Maternal and biparental care widespread, as adults protect nymphs

290
Q

Isoptera

A

-Termites
-Most ancient lineage to develop eusociality
-Mounds act as homeostasis mechanisms (another extended phenotype) by facilitating airflow
-100s of years old
-Mounds/colonies alter soil, plant growth, tree distribution and levels of nitrogen fixation (changes distribution of nutrients in soil, altering what plants can and cannot grow)
-Was difficult to define termites

291
Q

Why was it difficult to define termites

A

-Were considered an order
-Molecular work revealed termites form monophyletic group within cockroaches
-Termites are actually eusocial cockroaches

292
Q

Eusociality

A

Differentiation of ‘roles’ in colonies to form morphologically different castes, including soldiers, fungal farmers, workers etc)

293
Q

Hemimetabola

A

-Thysanoptera (thrips)
-Hemiptera (true ‘bugs’)

294
Q

Thysanoptera (thrips)

A

-Wings strap-like with fringe of long setae
-Right mandible reduced, left mandible inflexible to scrape cell content from plants
-Pre-adult instar inactive and non-feeding until final mount
-Haplodiploid (males produced from unfertilised eggs)
-Most feed on plants or fungi
-Some species within galls (cancerous growths of plants caused by scraping of cells and salivary content) are eusocial
-Important pests of plants

295
Q

Hemiptera feeding

A

-Mouthparts fused to form piercing, sucking beak, or rostrum
-Mostly herbivorous and feed on plant vascular tissue, such as phloem sap and xylem fluid
-Major plant pests
-Can be predaceous

296
Q

Reproduction in hemiptera

A

Viviparity, and parthenogenesis in some groups

297
Q

Hemiptera groups

A

-Sternorrhyncha (psyllids, aphids, whiteflies, scale insects)
-Auchenorryncha (cicadas, cercopids, membracids, fulgoroids)
-Heteroptera

298
Q

Phloem sap for insects

A

-Sugary sap flowing to roots from leaves
-Positive pressure
-This is a challenge because it is in the vascular bundle (hard to penetrate) and lacks nitrogen
-Insects thus need adaptations to deal with the high levels of sugar and low levels of nitrogen, such as honey dew secretion

299
Q

Xylem fluids for insects

A

-Dilute, nutrient poor flow to leaves
-Negative pressure (leaf transpiration)
-Requires force to extract against flow
-Insect thus needs adaptations to overcome this, such as extremely powerful muscles, and a cibarial pump housed in the expanded forehead and used to break the flow

300
Q

Sternorrhyncha

A

-Have fine, hairlike stylets
-Parthenogenetic viviparity
-Reduced or lost ovipositor
-Phloem feeding (and honeydew secretion)
-Aphids have adaptations that allow it to ‘search’ cells for content

301
Q

Sternorrhyncha endosymbiosis

A

-Bacteria are housed in specialised host cells
-Bacteriome organ for housing bacteria
-These help extract nutrients from phloem

302
Q

Auchenorrhyncha

A

-Elaborate acoustic organs on legs
-Enlarged clypeus (forehead)
-Cibarial pump
-Xylem feeding

303
Q

Heteroptera synapomorphies

A

-Beak attached to front of head
-Flat folded wings, overlapping abdomen
-Hemelytrous forewings
-Scent glands on nymphs (anti-predator)
-Some predators

304
Q

Holometabola

A

-Also known as endopterygota
-Coleoptera (beetles)
-Lepidoptera (moths and butterflies)
-Hymenoptera (bees and ants)
-Diptera (flies)

305
Q

Prothorax

A

The anterior (first) segment of the thorax of an insect, not bearing any wings, but does bear first pair of legs

306
Q

Pronotum

A

The dorsal plate of an insect’s prothorax

307
Q

Parthenogenesis

A

Development of an embryo from an unfertilized egg cell

308
Q

Setae

A

Stiff hairlike structures

309
Q

Haplodiploidy

A

Sex-determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid.

310
Q

Instar

A

Developmental stage of arthropods, such as insects, between each moult (ecdysis), until sexual maturity is reached

311
Q

Cyclopean metasternal ear (in mantises)

A

A single (cyclopean) ear on the ventral plate of the third or last segment of the thorax of insects (metasternal)

312
Q

Crypsis

A

Ability of an animal or a plant to avoid observation or detection by other animals

313
Q

Coriaceous

A

Leathery

314
Q

Ovariole

A

Tubular component of the insect ovary, and the basic unit of egg production

315
Q

Ocelli

A

Simple eye

316
Q

Cerci

A

-Paired appendages on the rear-most segments of many arthropods, including insects
-Many forms of cerci serve as sensory organs, but some serve as pinching weapons or as organs of copulation
-In many insects, they simply may be functionless vestigial structures

317
Q

Tarsi

A

-Comprise the foot or contact surface of the leg
-2-5 segments

318
Q

Trochanter

A

-Second leg segment of insects
-Small and can usually only move in one plane

319
Q

Coxa

A

-First leg segment of insect (counting from body)
-Attaches leg to thorax

320
Q

Femur in insects

A

-Third leg segment of insects
-Often thickest segment

321
Q

Tibia in insects

A

-Fourth leg segment
-In many species, it is covered in spines and hairs
-In bees, the pollen basket is found on the tibia of the hind leg

322
Q

Old name for Epiprocta (dragonflies)

A

Anisoptera

323
Q

Anterior vs posterior

A

-Anterior describes the front
-Posterior describes the back

324
Q

Ventral vs dorsal

A

-Ventral describes lower surface
-Dorsal describes upper surface

325
Q

Elytra

A

-First set of wings that are modified to form hard shell
-Common in beetles

326
Q

Mesothorax

A

Second or middle segment of thorax bearing second pair of legs and anterior (first) wings

327
Q

Metathorax

A

-Third or last segment of thorax bearing hind legs and wings

328
Q

Puparia

A

Thickened, barrel-like larval skin within which the pupa is formed

329
Q

Tergum

A

Upper or dorsal surface of any one body segment of insects

330
Q

Coleoptera (beetles)

A

-4 suborders, 166 families, and ca. 400-420,000 species (40% of all insects), 400 species in UK alone
-Extraordinary diversity in ecology, morphology, behaviour, high in every terrestrial habitat
-Repeated evolution of aquatic adaptations

331
Q

Coleoptera synapomorphies

A

-Elytra
-Large hindwings with specialised venation for ‘tucking’ and for powerful flight
-Reduced thorax
-Retracted genitalia

332
Q

Why do beetles have a hard exterior?

A

-Gives access to hard habitats and spaces
-Protects wings
-Protects from infection and protection
-Provides homeostasis (desiccation, cold)

333
Q

Desiccation

A

Removal of moisture

334
Q

Ecology of beetles

A

-Most herbivorous (roots, stems, leaves)
-Fungivorous
-Predaceous
-Peculiar diets (eg pure cellulose/lignin, dried grain)
-Parasitic (very uncommon)

335
Q

Lignin

A

Complex plant-derived polymer found in the cell walls of almost all dry-land plants

336
Q

Honeydew secretion in Hemiptera

A

-Honeydew is a sugar rich liquid produced
-When their mouthpart penetrates the phloem, the sugary, high-pressure liquid is forced out of the anus
-It is to deal with the high sugar levels in the phloem sap

337
Q

What 3 key insect innovations arose?

A

-Wings
-Evolution of wing-folding mechanisms
-Holometabolism

338
Q

How many times did wings evolve in insects?

A

Once

339
Q

Basic insect wing structure

A

-Under the wing membrane of insects are a network of veins to provide support
-Some have scales and/or fibres

340
Q

Variety in insect wings

A

-Wasps have no venation at all, with sheet-like wings
-Some have no membranes, only feather-like structures

341
Q

Pleural hypothesis for wing origin

A

-Gills gave rise to wings
-Gill structures in Odonata do resemble wings
-Surface skimming suggested as an intermediate function
-Expression of wing genes and tissues reduced in pleural zone

342
Q

Paranotal hypothesis for insect wing origin

A

Thoracic outgrowths gave rise to wings

343
Q

What natural selection pressures would have given rise to wings

A

-Elaborate patterns for courtship
-Thermoregulation, by heat gathering or fanning
-Skimming and gliding, aerodynamics
-Respiration

344
Q

Is the pleural or paranotal hypothesis correct?

A

-Thought that parts of both are correct
-Dual origin, wings are derived from selective regulation of HOX genes in tissue from thorax and pleural zones

345
Q

Insect pterothorax

A

-Combines actions of thorax and position of wings to drive flight
-Muscles simply relax or contract, pushing and pulling on thoracic segment (exoskeleton), contorting it
-This contortion moves wings up and down due to being attached by a notal hinge
-Muscles therefore provide indirect power
-Longitudinal muscles directly influence angle
-In basal orders, more power from direct muscles (e.g., Odonata)

346
Q

Adecticous

A

Having no mandibles

347
Q

Maxillae

A

-Part of an insect’s mouthparts
-Paired and arranged behind the mandibles

348
Q

Galls

A

Abnormal growths formed in response to the presence of insect larvae, mites, or fungi on plants and trees, especially oaks

349
Q

Aquatic adaptations in diving beetles

A

-Modified hind legs with setae that allow them to act as paddles
-Carry an air bubble underneath them

350
Q

4 main Coleoptera clades

A

-Polyphaga, 137 families, 315,000 species
-Adephaga, 8 families
-Archostemata, 4 families
-Myxophaga, 5 families

351
Q

Examples of Polyphaga

A

-Scarabeiformia
-Elateriformia
-Cucujiformia
-Chrysomeloidea
-Also includes stag beetles, leaf beetles, weevils and dung beetles

352
Q

Polyphaga and plants

A

-Overwhelmingly herbivorous
-Each specialised to feed on specific plants
-Thought that insect-plant coevolution is main driver of beetle diversity, but evidence is limited

353
Q

Scarabeiformia

A

-Scarabs
-Highly modified prothorax for burrowing
-Clavate or lamellate antennae
-Scarabeiform larvae (worm-like)
-Phytophagous mainly

354
Q

Phytophagous

A

Consumes plant matter

355
Q

Types of insect antennae

A

-Clavate antennae terminate in a gradual club or knob
-Filiform antennae are slender and thread-like in form
-In lamellate antennae, the segments at the tip are flattened and nested, so they look like a folding fan
-Plumose antennae have fine branches, giving them a feathery appearance

356
Q

Elateriformia

A

-Long lived larvae, short lived adults
-Dominated by the Elateridae (click beetles)
-Include potato click beetle (wireworm)

357
Q

Cucujiformia

A

-Dorso-ventrally flattened
-Associated with wood or leaf litter
-Includes Lymexylidae (ship timber beetle) and Tenebrionidae (darkling beetles, grain pests)
-Some predatory, such as Meloidae (blister beetles)

358
Q

Lytta vesicatoria (Spanish fly)

A

-Males produce cantharidin (toxic aphrodisiac in humans and birds) as a nuptial gift along with sperm and female coats eggs with it as chemical protectant
-Hypermetamorphosis, as when eggs hatch, first instar is known as triungulin larvae and is morphologically distinct, while following stages are normal
-Larvae crawl up grass and flower stems and latch on to bees
-Larvae are taken to bees hive, where they eat all bee larvae

359
Q

Examples of Chrysomeloidea

A

-Chrysomelidae (leaf beetles)
-Curculionidae (weevils)
-Cerambycidae (long-horned beetles)

360
Q

Adephaga

A

-Mostly predatory
-Dominated by Carabidae (ground beetles) and aquatics (e.g., diving beetles)
-Includes bombardier beetles (Stenaptinus insignis)

361
Q

Anti predator chemical weapon in bombardier beetles

A

-Aqueous reservoirs inside beetle hold hydrogen peroxide and hydroquinone
-When beetle is disturbed, muscles contract, opening a valve and flushing chemicals into ‘vestibule’ (entrance/exit zone)
-Lining vestibule are glands containing peroxidise enzymes that catalyse reaction between the chemicals
-Reaction is exothermic, and essentially explodes out of the beetle, with valves in the vestibule creating a pressure gradient that expels the liquid away
-Can alter angle of attack
-Can be used after being eaten to stimulate regurgitation

362
Q

Chemoreception in insects

A

-Detection of chemicals in environment
-Can be olfactory or via contact
-Sensillae can be found on antennae, mouthparts, legs
-Rely on movement of chemical through pores into sensillum lumen, where receptors will bind to specific chemicals, creating nerve depolarisation and sending a message to the brain (Olfactory glomeruli)
-Olfactory chemoreception allows long distance location of resources and mates
-Can be highly specific
-Different insects have differently adapted mechanisms
-Most important sensory modality

363
Q

Semiochemicals

A

-Information chemicals
-Pheromones (within-species communication)
-Allelochemical (between species communication)

364
Q

Example of insect chemoreception adaptation

A

Male moths have plumose antennae that are finely divided to maximise surface area for sensillae

365
Q

Example of highly specific chemoreception in insects

A

-S-sulcatol and R-sulcatol are two orientations of the same molecule
-Produced by two different beetles species
-Despite molecules being same, species are reproductively isolated
-Receptors are specific enough to detect isomers

366
Q

Mechanoreception in insects

A

-Detection of mechanical distortion of the body
-Touch, vibration, strain and stress
-Trichoid sensillum

367
Q

Sensory perception adaptations in insects (particularly beetles)

A

-Chemoreception
-Mechanoreception
-Thermal and hydro reception
-Visual reception

368
Q

Insect trichoid sensillum for mechanoreception

A

-Hairlike
-Depolarisation of nerve caused by bumping of scolopale, a sheath surrounding the nerve ending
-When external hair is touched, it bends and causes a ‘peg’ to hit the scolopale, sending a signal to brain

369
Q

Thermal and hydro reception in insects

A

-Water and temperature control very important
-Very little known about these receptors

370
Q

Visual reception in insects

A

-Ommatidium (compound eye)
-Ocelli (simple eyes), made of lens and rhabdomes, mainly for circadian rhythms
-Stemmata, found in larval holometabolous insects and occur laterally on head

Zoology Y2 (2 decks)

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