all Flashcards
what are the 6 kingdoms and give a feature of each
- monera (prokaryotes)
- protista (eukaryotic, single celled)
- fungi (heterotrophic, walls of chitin)
- plantae (photosynthetic, autotrophic)
- animalia (heterotrophic)
- archaebacteria (anaerobic)
how many phyla of animals are there believed to be?
40
what is the order of the geographical periods starting from quaternary?
quaternary, tertiary, cretaceous, jurassic, triassic, permian, carboniferous, devonian, silurian, ordovician, cambrian, ediacaran, precambrian
when (period) were the earliest animal and prokaryote fossils?
precambrian
animal- 1700mya
when was there glaciation in the southern hemisphere?
carboniferous
what environmental events occured in the Quaternary?
cooler glacial conditions, south polar ice cap forms, human evolution in last 5-3 my
what is the burgess shale
soft bodied fossil bearing deposit (fossils from cambrian explosion) discovered by Walcott in 1909
- mostly benthic forms
what 2 physical factors are important in animal evolution?
climate change and continental drift
describe glaciation
climate change causes glaciation and it leads to isolation and separation of pops as they differentiate genetically. ice disappears and distinct species and populations appear.
hybrid zones where previously isolated species meet
describe continental drift
Alfred Wegener proposed the idea in 1915. land masses once joined into supercontinent pangea but masses separated by continental drift due to plate tectonics. earths crust is comprised of 7 large plates floating on the mantle
a) what 4 problems must animals solve to survive?
b) what must the body design be correlated with to meet these?
a) 1. getting food and O2 2. maintain salt and water balance 3. remove waste 4. reproduction b) 1. environment 2. size of animal 3. mode of existence 4. genome constraints
what % earths surface marine and roughly what % vertebrates are fish?
71%
50%
which 2 zones are within the neritic zone- give depths and features
- eulittoral (between rise and fall of tide- animals adapted to exposure like barnacles)
- continental shelf/sublittoral (150-200m, sunlight benefits algae, coral reef is symbiotic relationship between poly and algae
what 8 zones are within the oceanic zone and give depths?
- continental slope (shore-3000+m)
- epipelagic (200m)
- mesopelagic (300-1000m)
- bathypelagic (1000-2000m)
- abyssopelagic (2000-3000m)
- hadalpelagic (3000+m)
- abyssal plain (3000-5000m)
- mariana trench (11,000m)
whats the difference between photic and aphotic zones?
light can penetrate photic zones and it is anywhere up to 200m deep. aphotic zone has increased pressure, decreased light and temp, more scarce food source, different feeding mechanisms
give an example of an animal that can survive in the eulittoral or sublittoral zone
epaulette shark- when tide out lives in eulittoral zone, when low O2 can shut down its body but keep the flow to the brain and can use its fins to move in the pools
give 2 examples of deep sea animals
anglerfish- light produced by bacteria help it survive by drawing in prey.
harp sponge- usually filter feeders but are carnivorous in deep sea
define
a) pelagic
b) benthic
c) errant
d) sessile
e) sedentary
a) suspended or swimming
b) bottom
c) mobile
d) attached
e) unattached, immobile
what is coastal upwelling?
as the sea moves there is water exchange between higher and lower waters and nutrients move from the bottom to the top
give 11 advantages of the ocean
- space- high productivity (28 x 10*9 c/yr)
- biomass decreases from shoreline to open ocean
- biomass decreases towards tropics (tropical waters have less temp change so less movement)
- salinity 3.4-3.6%
- oxygen
- water movement constant
- deep ocean currents- saltier water sinks moving slowly along bottom
- iso-osmotic with body tissue fluids of many animals (osmoconformers, invertebrates will retain solutes to increase body conc)
- buoyancy
- fertilisation and development (external)
- waste as ammonia
give 4 brief features of a marine environment
- constant salinity, temp, O2
- provides support
- medium for fertilisation
- waste as ammonia
give 6 brief features of a freshwater environment
- less constant temp, O2, velocity, volume
- osmotic regulation needed
- support
- eggs retained by parent
- direct development
- waste as ammonia
give 4 brief features of a estuarine environment
- seasonal variations
- fresh and sea water mix
- support
- waste as ammonia
give 6 brief features of a terrestrial environment
- daily and seasonal temp extremes
- O2 constant and uptake needs moist surface
- can suffer water loss
- no support
- internal fertilisation
- waste as urea/uric acid
what generally happens to the lake condition in summer?
epilimnion (O2 rich) seperated from hypolimnion (O2 poor) by broad zone thermocline in summer due to rapid change in temp and O2 with increasing depth
what happens as body size increases?
SA:V decreases and mechanisms other than diffusion are needed
are free moving organisms often bilaterally or radially symmetrical?
bilaterally
give an example of a constraint of the genome
there are limitations imposed by the ancestral design which are controlled by the animals genetic makeup- for example molluscs have the same basic body plan that is modified in different ways
give 6 features of protozoans
- single celled
- eukaryotic
- motile
- heterotrophic
- have pellicle (cytoskeleton and cell membrane)
- have test (hardened outer structure)
describe locomotion of protozoans
- flagella to propel
- cilia beating in metachronal waves
- pseudopodia
in what 3 ways is food acquired by protozoans?
and what digests the contents?
- pinocytosis (high conc food particles outside cell and low inside- pinched into vesicle)
- receptor mediated endocytosis (receptors on cell membrane bind with molecules, engulfed into vesicle)
- phagocytosis (large food particles bind to receptors and form vesicle)
lysosomes digest contents
how did the protozoans originate?
the endosymbiont theory- occured to utilise O2 as levels increased in atmosphere:
- plasma membrane of ancestral prokaryote infolds
- cell with nucleus and endomembrane systems engulfs aerobic heterotrophic prokaryotes by endocytosis
- ancestral heterotrophic eukaryote formed with mitochondrion
what are the 4 types of protozoan?
amoeboid
apicomplexans
flagellates
ciliates
what are the 2 types of pseudopodia?
lobopodia (more rounded)
filopodia (spikey)
describe amoeboids
asexual, move by pseudopodia, free- living (amoeba) and parasitic (E.histolytica)
describe the life cycle of amoeboid E.histolytica
- usually from faeces or uncooked food as a cyst that can survive 2-5 weeks in faeces
- non pathogenic E.dispar form eats bacteria
- virulent form invades mucus lining and causes an abscess to form
- amoebe may reach bloodstream, liver, lungs, brain but is treatable
describe apicomplexans
spore forming, sexual and asexual, spread by sporozoites, parasitic (plasmodium)
describe lifecycle of apicomplexan plasmodium
species include: P.vivax, P.ovale, P.falciparum, P.malgrige
- sporozoites divided at liver cells by fission forming merozoites
- merozoites enter infect red blood cells (asexual division)
- break out of RBCs, some develop into gametocytes
- mosquito bites human picking up gametocytes in blood
- gametes develop from gametocytes
- fertilisation in mosquito gut forms diploid zygote
- oocyst develops
- sporozoites develop in oocyst, migrate to salivary glands
- mosquito bites human, transferring sporozoites
how can we attempt to control malaria?
drug treatment, GM males to attempt to sterilize them, gene editing for females so they don’t produce eggs
what is apicomplexan toxoplasma gondii?
cat is the definitive host where the parasite reproduces and the rodent is the intermediate host which transmits the parasite. parasite influences host making them less afraid of cats when infected so more likely to go near the cats to pass it on
a) describe flagellates
b) describe its free living form
a) asexual (binary fission), move by flagella, free living (trichonympha) and parasitic (trypanosoma)
b) trichonympha is in the gut of roaches and termites who eat cellulose which cant be digested. trichonympha breaks down cellulose into glucose producing enzyme B-glycosidase
explain flagellate Trypanosoma brucei
- causes sleeping sickness
- has variant surface glycoproteins so is hard for immunity to be developed
- transmitted by tsetse fly
- sub species Gambiense: fly human fly, if untreated death 2-3 years
- sub species Rhodesiense: fly game fly, death 6-8 weeks, zoonosis can occur
- thought tsetse fly attracted to plain surfaces emitting even light
- can trap tsetse flies using the smell of cow urine
describe ciliates
asexual (binary fission- macronucleus), sexual (conjugation- micronucleus), move with cilia, free living (paramecium)
describe ciliate paramecium
- usually in ponds or freshwater
- feed on micro-organisms
- cilia waft food into oral groove and are used in locomotion
- contractile vacuole controls water and expels excess liquid
what are the 3 types of ova?
- isolecithal (little yolk, evenly distributed)
- telolecithal (yolk concentrated towards vegetal pole)
- centrolecithal (yolk concentrated at centre)
describe the stages during the acrosomal reaction in sea urchins
- egg has protective jelly coat with chemoattractant properties causing sperm to migrate towards signals
- sperm contacts the jelly coat and acrosomal vesicle with hydrolytic enzymes digests the jelly coat
- acrosomal process forms and extends due to polymerisation of protein actin
- process is coated with bindin which locks onto bindin receptors on vitelline layer
- contact is made to egg pm stimulating sodium ion flow into egg, changing egg pm to positive
- sperm cant cant on and are repelled (fast block to polyspermy)
- sperm nucleus drawn into egg cytoplasm and fertilisation membrane forms and sperm and eggs merge
what is the cortical reaction and slow block to polyspermy?
- ca released from cytoplasm causes cortical granules to be released and fuse with plasma membrane
- enzymes and solutes digest adhesion between pm and vitelline layer
- vitelline layer polymerised by some enzymes becoming hardened
what does the potential of the egg pm changing lead to?
- metabolic changes in the egg
- increase in protein synthesis and O2 consumption (prep for development)
- ph change
in sea urchin after how long
a) sperm and egg merge
b) replication and first division
a) 20 min
b) 90 min
what are the 3 early stages of development?
cleavage, gastrulation, organogenesis
what is cleavage and the 2 types?
- rapid division of a single cell into a ball of cells known as blastomeres
- can be complete or incomplete
- radial cleavage is where the mitotic spindles are parallel/perpendicular to vertical axis for second division, cells form on top of others, cleavage is indeterminate (fate not fixed early on), organisms have top/bottom oral/aboral
- spiral cleavage is where the mitotic spindles diagonal to vertical axis of embryo, can cause twisting of embryo, mitotic spindles tilt, cleavage determinate, front/back anterior/posterior and top/bottom dorsal/ventral
- continued cell division forms a morula which forms a blastula
what are the 4 blastula types?
- coeloblastula (hollow, 1 cell thick wall)
- stereoblastula (ball of blastomeres)
- discoblastula (blastomeres at animal pole)
- periblastula (1 cell thick blastomere layer around yolky mass)
what is gastrulation?
blastula forms a gastrula with 3 tissue layers formed
- connectivity is lost at the bottom, blastopore forms which goes on to become mouth or anus
- endoderm and ectoderm form with mesoderm in the middle
what is the archenteron?
embryonic gut which the filopodia help to push up during gastrulation
whats the difference between endoderm, ectoderm, mesoderm?
ecto: outer layer, epidermis, CNS
endo: inner layer, gut, digestive tract, circulatory, respiratory
meso: middle layer, body cavity coelom, bone, muscle, blood
whats gastrulation in mammals like?
blastula forms trophoblast (placenta) or inner cell mass which forms epiblast (embryo) or hypoblast (extraembryonic membranes)
describe the 3 main body cavities
acoelomate: flatworms, lacks body cavity between gut and outer body
pseudocoelomate: roundworms, body cavity only partially lined by mesoderm
coelomate: earthworms, body cavity lined completely with mesoderm
what are the 2 cell types that can be formed after the 8 cell stage and describe them
protostomes
- spiral and determinate cleavage
- mesoderm formed by splitting of mesoderm (schizocoelous)
- mouth develops from blastopore
deuterostomes
- radial and indeterminate cleavage
- mesoderm formed from outpocketing of it (enterocoelous)
- anus develops from blastopore
how did porifera originate, what is the evidence and their likely ancestor?
from unicellular colonial flagellates around 700mya as flagellated cells are found in metazoans and many form colonies as well as molecular evidence links. choanoflagellates are the likely ancestor
give 11 features of phylum porifera
- parazoa branch
- simple structure
- successful and widespread
- ancient group
- rigid, sessile, perforated
- lack muscle, NS and organs
- usually hermaphrodite
- asymmetrical
- cellular level organisation
- mainly marine
- can form relationships with others to move such as on shells of hermit crabs
how do porifera forms vary depending on where found?
flat and low growing where lots of wave action but are larger where less current movement in deeper water so are large to get as much food as possible
briefly describe features of the structure of a sponge
- ostium
- osculum
- amoebocyte
- choanocyte
- spongocoel
- spicule
- water enters via incurrent pores (ostium)
- cavity opens via osculum and water is expelled here
- amoebocyte is where digestion occurs and food is taken from choanocyte and moved to other cells
- choanocytes waft flagella to create a current and enable water flow into sponge, they line the inside of the sponge
- spongocoel can help keep pores open
- spicule can be calcareous, siliceous or made of spongin fibres
how fast does water pass through a sponge?
at up to 20,000 times its volume in 24 hours
what happens as the sponge gets larger?
the bigger the sponge the larger the choanocytes so a bigger current is generated
give an example of a sponge
venus flower basket sponge- made of silicate and 75% tissues are syncitical (no cell boundaries between cells) and electrical impulses can travel through them
how do sponges feed?
most are filter feeders taking in organic material from water or bacteria trapped in choanocytes which the amoebocytes engulf. but some are carnivorous with modified spicules to catch prey (harp sponge)
why are filter feeder sponges important for coral reefs?
they generate nutrients. the ocean is poor in N and P. the C in the water is taken up by sponges and as bits of them die they are eaten by others so the other organisms then get the C
can sponges regenerate?
in 1907 Wilson discovered that sponges can regenerate
- put sponges through a sieve to see if reform and they did
- also he mixed 2 different sponges before sieving and found they reformed as separate sponges and this was evidence for immunorecognition
how do sponges reproduce asexually?
by budding or gemmules (internal buds that remain viable in harsh conditions and can form a new organism when conditions favourable)
how do sponges reproduce sexually?
- usually hermaphrodite
- sperm expelled by osculum and engulfed by choanocyte
- moved around sponge until egg is reached
- larvae retained until blastula stage
how are sponges biochemical agents?
- some produce biotoxins
- bright colours indicate toxicity
- some chemicals have antibacterial activity
what 2 branches does eumetazoa divide into?
radiata and bilateria
give 8 features of cnidarians
- 2 body layers: epidermis/outer and gastrodermis/ inner
- mesoglea between the 2
- limited organ development
- simple form: blind sac with gastrovascular cavity
- mouth=anus
- simple nerve network and no brain
- bundles of microtubules act as muscle
- 2 forms exist: poly and medusa
what do these cell types do in cnidaria?
- cnidocil
- epitheliomuscular cell
- interstitial cell
- neuron
- enzymatic gland cell
- cnidocil: contains nematocysts, cover the tentacles
- epitheliomuscular cell: muscle system
- interstitial cell: can transform into other cells
- neuron: forms nervous system
- enzymatic gland cell: discharges enzymes into gut
what occurs at the gastrodermis?
digestion occurs intracellularly after reaching the gastrovascular cavity
what is a nematocyst?
- designed to capture and stun prey
- contain coiled, hollow, barbed thread to ward off enemies or capture prey
- stimulated mechanically and chemically
- ca builds up, osmotic pressure changes
- thread uncoils when stimulated and penetrates and paralyses prey
- often inject venom/toxins
whats key about the glaucus sea slug?
glaucus sea slug is a mollusc but it has nematocysts like cnidarians due to eating cnidarians and retaining the nematocysts as a form of defence
what are the 4 main cnidarian classes?
- hydrozoa
- scyphozoa
- cubozoa
- anthozoa
give 3 features of hydrozoans
- usually colonial
- sometimes show secondary polymorphism where polyp stage/parts can take on different functions
- float
whats the difference between the gastrozooid and gonozooid?
in cnidarians gastrozooid is for feeding and gonozooid is for reproduction
what is hydra?
freshwater hydrozoan with no medusa stage and no planula larval stage
what are siphonophores?
the most sophisticated hydrozoan- clusters of feeding polyp colony with individuals of different functions hanging below the swimming bell connected by a logn stem
give 8 features of scyphozoans
- medusa phase dominant
- increase in sea temp can cause them to move to areas they aren’t usually found with little nutrients and can disrupt food chains
- radial symmetry
- outer epidermis and inner gastrodermis separated by jelly like mesoglea
- muscle cells allow umbrella to pulse for movement, as well as relying on currents
- simple eye- pigment cup
- statocyst senses gravity
- rhopalium are nerve cells that can control rhythm of pulsations
give 6 features of cubozoa
- toxic (nematocysts can be venomous)
- active swimmers (2m per second)
- pursue prey such as fish
- four evenly spaced tentacles
- sophisticated eyes
- can use navigation signals from shoreline and land to orientate and navigate themselves
give 8 features of anthozoans (sea coral/anemone)
- polypoid
- colonial or solitary
- medusa phase absent
- water entering allows it to become rigid
- water can circulate, entering via septal perforation- good for diffusion and respiration
- septum increases SA
- hollow tentacles
- thick mesoglea
how do anthozoans reproduce asexually?
- pedal laceration: slide along base dropping off bits of themselves
- longitudinal fission: strip down the middle forming 2 individuals
how do anthozoa reproduce sexually?
- hermaphrodite
- fertilisation in gastrovascular cavity or the sea
- planula larva produced
describe the symbiotic relationship between clownfish and anemone
- clownfish lives in anemone tentacles but doesn’t trigger nematocysts
- fish benefits from feeding on what anemone has and gets protection
- anemone benefits as fish helps increase O2 and nibble the tentacles to keep it clean
describe the symbiotic relationship between anemones and stony coral
- carbon is fixed by zooxanthellae (photosynthetic algae in gastrodermis)
- polyp generates waste, picked up by algae
- food is caught by coral
- zooxanthellae obtain inorganic ions from sea and aid in deposition of calcium carbonate reef skelton
- if no zooxanthellae coral bleaching occurs
within cnidarians what is the brief phylogeny?
anthozoa-> hydrozoa -> scyphozoa (medusa stage more derived as is only in the last 2 groups)
give 9 features of platyhelminthes
- bilaterally symmetrical
- protostomes
- no coelom (acoelomate)
- triploblastic (3 body layers)
- cephalisation
- organs
- dorso ventrally flattened
- simple internal structure
- no blood system, rely on diffusion
- gut has one opening
- simple excretory system involves the protonephridia (flagella waft fluid into it, absorbing useful substances)
what is xenacoelomorpha?
basal bilateral simple structured organism that was thought to be platyhelminthes but aren’t
what are turbellarians?
free living platyhelminthes, non parasitic
- covered in epidermis
- nervous tissue concentrated at anterior end
- the auricle detects chemicals
- simple eye detects light
- male and female reproductive tissue
how was the regeneration of platyhelminthes studied?
- investigated if will reform when chopped up, they did
- further down cut, longer head takes to form
- small section cut then 2 heads can form
- cells are pluripotent, being able to form any other cell in the body so regeneration can occur
- studied further by Thompson and McConnell in 1950s/60s
- trained flatworms ro be shocked when bright light displayed
- cut up worms and reformed and both halves responded as though shocked
- fed trained worms to untrained and they responded with shock response
BUT observer bias proven
what is penis fencing in platyhelminthes?
being female is costly so fight for which of the pair becomes the female. fight with penis to try to inseminate the other first
give 6 parasitic adaptations of platyhelminthes
- loss of unwanted organs
- penetration devices (enzymes produced so can burrow into host)
- attachment devices (suckers/hooks)
- protective devices (covering/ produce chemicals to stop digestive enzymes working)
- transmission via vector
- production of eggs in large numbers
how many more eggs do parasitic flatworms produce than free living flatworms?
10,000-100,000 times more
give 4 features of flukes- trematodes (platyhelminthes)
- found inside animals
- have tegument (tough covering) that is non ciliated syncytium (no cell boundaries)
- have oral and ventral suckers
- mostly full of reproductive tissue
describe the generalised life cycle of a fluke
- egg hatched in water
- intermediate host usually a snail- miracidium form here
- germinal cells formed in sporocyst
- redia formed
- develops into cercaria with ventral and oral sucker
- larvae released from snail to swim to second host- metacercaria formed
what do blood flukes/ schistosomatidae do?
- cause schistosomiasis
- worms burrow into skin of human host and live in veins of intestine which can lead to blood in the urine
what does D.spathaceum fluke do?
causes cataracts to from on eyes of intermediate host fish so are more likely to be predated by final host sea bird
what does the lancet fluke do?
balls of mucus containing larvae are eaten by intermediate host ants causing them to clamp onto grass strands when colder weather making themselves more vulnerable to being eaten by final host cow/sheep
how can trematodes be cooperative?
different forms of flukes can group cooperatively to carry out a function
- soldier groups are aggressive, smaller and non reproductive
- reproductive groups
give 7 features of cestoda (platyhelminthes)
- live in gut
- tegument
- no gut themselves
- scolex is the head region
- strobila are the repeated segments
- intermediate hosts
- full of reproductive tissue
what does the beef tapeworm (T.saginatus) do?
- enters muscle tissue of cow
- bladder worms form in muscle tissue
- human infected by ingesting meat if not cooked properly
when does self fertilisation occur in tapeworms?
when only 1 tapeworm in host
mature as males first then females- sperm can be transferred to functional female area
what are advantages of having a coelom?
- transport: movement of nutrients in fluid and gas exchange can occur)
- gut moves independently of body wall
- site for gametic maturation in fluid
- hydrostatic skeleton (rigid but allows for movement)
annelids can move by peristalsis describe this
- wave of muscle contraction
- penetration anchor prevents back slipping when burrowing into sediment, the long thin circular muscles contract
- terminal anchor allows for trailing part of body to be puleld forward, short fat longitudinal muscles contract
a) what is the benefit of metameric segmentation in annelids?
b) what is the prostomium and pygidium?
a) makes locomotion more efficient and precise
b) head and tail
in annelids which structures run the length of the animal and which are repeated in each segment?
- gut and nervous system run length
- nephridium openings repeated
in annelids what does the septum and nephridium do and what kind of circulatory system do they have?
septum divides segments, nephridium acts as a kidney and closed circulatory system
in what 3 ways can segmentation be modified by?
- restriction of structures to particular segments (reproductive tissue only in certain segments)
- some segments develop special structures (head)
- segments may fuse together
describe ultrafiltration in annelids
- ultrafiltration site is on a blood vessel forming primary urine
- modification occurs to produce final urine which is released to the exterior
- modification involves reabsorption of useful metabolites and secretion of toxins from blood or coelomic fluid
- pressure of ultrafiltration due to muscular contractions of vessel wall
what are the 3 main groups of annelids
- polychaeta
- oligochaeta (clitellata- earthworms)
- hirudinea (clitellata- leeches)
give 3 features of polychaetes (annelids)
- parapodia and lots of bristle like setae
- each segment has a pair of parapodia (gas exchange occurs here and it increases SA)
- prostomium (head) well developed
describe the 2 groups of polychaetes: errant and sedentary
errant - move a lot - well developed parapodia - active hunters - ragworm sedentary - tube dwelling - suspension feeding (water current passes between tentacles, tracts remove matter directing it to longitudinal food groove, large particles rejected and smaller ingested - sabella
describe arenicola
- polychaete
- sedentary
- live in burrows/tubes
- reduced parapodia as are burrowers
- draws in sand to feed from one end of the burrow and deposit waste at the other end
what is polychaete reproduction like?
dioecious, external fertilisation, spawning can be synchronous
some polychaetes undergo epitoky, what occurs?
it is a body transformation such as metamorphosis into a reproductive form so can swim for longer, or will only spawn at a particular time of year
give 4 general features of clitellata
- no parapodia
- produce clitellum and cocoons (clitellum helps produce cocoon which is where eggs develop and are fertilised)
- hermaphrodite
- gonads are restricted to a few segments
give 7 features of oligochaetes/earthworms
- few setae
- peristaltic locomotion
- well developed septa used in peristalsis
- some live on surface and some burrow
- some feed on soil or bring food from surface into soil
- gas exchange occurs on outer surface
- reproduce by mutual sperm transfer
describe reproduction in lumbricus worm
mutual sperm transfer
- worms pair up head to tail bound by substance produced by clitellum
- sperm released by male gonopore of 1 male travelling down sperm groove to opening of the other
- clitellum produces lots of mucus and the cocoon
- sperm is passed to female gonopore and eggs and new worms develo in cocoon
give 10 features of hirudineans (annelid)
- no setae
- restricted to 34 segments
- mutual sperm transfer
- no clear division of septa
- predaceous
- jaw like structures
- eat small inverts
- blood suckers (produce anticoagulant hirudin)
- use symbiotic bacteria to break down blood and can take up to 10X body weight in blood
- crawl with suckers as have no septa and the well developed longitudinal muscles aid the movement
give features of a generalised mollusc
- visceral mass surrounded by mantle covering which secrete shell if they have one
- mantle cavity contains gills and cilia cause movement across the gill
- nerve ring with branches goes to visceral mass and foot
- foot can be used for movement (muscles act antagonistically acting on cells filled with fluid to develop waves of contraction)
- radula is a feeding device of a conveyor belt of teeth that grind away at algae
- open circulatory system
- body plan very plastic
- seven different types of mollusc
describe the circulatory system of molluscs
open- in the haemocoel
- oxygenated haemolymph pumped from ventricle to haemocoel bathing organs
- drains into channels, chambers and branchial vessels
- O2 picked up by conidia and transported to atria and ventricles an back to haemocoel
what 4 changes make gastropoda different from the standard mollusc?
- development of head
- dorso ventral elongation of body (often coiling of visceral mass)
- shell forming a protective shield
- torsion
what is torsion and the advantage of it?
- protection of veliger larva stage
- protection of adult
- utilisation of oncoming water by gills
what is a disadvantage of torsion and how has this been combatted?
anus over head
- modifications of mantle cavity to solve sanitation problem and water flow
what is de-torsion?
undergone torsion but then gone back to normal as still have some twisting to do which occurs due to differential growth and muscular contraction- such as sea slugs
what are the 2 types of spiralling in gastropods?
planospiral- symmetrical
conispiral- asymmetrical
initially thought to be planospiral but now conispiral as shifted over to the right side
what are the most specialised gastropods?
pulmonates
- no gill and mantle becomes vascularised into a lung wall
- evolved when O2 short so needed another way to access it
- can exploit terrestrial environment
- hermaphrodite
what is partula?
- gastropod that is species rich on the islands of tahiti
- issue with predator african land snail
- introduced predator rosy wolfsnail to eradicate african land snail but actually preferred partula snail
what are lamellibranchs?
filter feeders
give 8 features of bivalves
- most are lamellibranchs
- most dioecious
- laterally compressed
- shell made up of 2 hinged parts
- reduced head and nervous system
- no radula
- can use foot for feeding with cilia gathering food
- draw in water into mantle cavity over gills
give 3 examples of bivalves
a) mussels- attach themselves to rocks as are in intertidal zone due to byssus threads (strong silky fibres made from proteins to attach to rocks
b) giant clams- have symbiotic relationships with algae for additional C source
c) scallops- eyes on mantle cavity and can use shells for movement
give 14 features of cephalopods
- marine carnivores
- orientation of body changed
- shell reduced/lost
- closed circulatory system
- foot modified into tentacles
- mantle cavity relies in muscle contraction not cilia
- can move by jet propulsion
- some have ink sac which releases ink with irritant forming cloud so predator cant see
- chromatophores in skin mean can change colour for disguise or mating
- well developed nervous system (good memory and learning skills)
- well developed eyes
- not good at picking up sound
- radula present so can produce neurotoxins
- water pumped by muscular action
describe the circulatory system of cephalopods
closed
- have main heart and accessory hearts
- blood pumped into gills
- high metabolic rate and are active predators
what are nautiloids?
molluscs
- first appeared in cambrian
- animals live in end of chambered shell which is filled with air rather than water to aid with buoyancy
- can change amount of air and fluid in chambers
- simple eye
what does coleoidea include?
cuttlefish
- internal shell/cuttlebone used as buoyancy device
squid
- shell reduced to proteinaceous pen for support
octopus
- shell vestigial/absent
give 9 features of arthropods
- largest animal group
- metamerically segmented
- appendages on segments
- grouped with nematodes as both undergo molts
- marine, freshwater and air
- no peristalsis but muscles are attached to cuticle
- open circulation using haemocoel
- special structures for gas exchange as body impermeable to gas
- growth by ecdysis
in arthropods how are they evolutionarily modified?
- groups of segments specialised (tagmatization)
2. specialisation of appendages
what is a cephalothorax?
where the head and thorax join
do arthropods have hox genes?
yes- first discovered in drosophila
- controls anterior posterior axis
- tells cells which segment they are in
- highly conserved
describe the cuticle in arthropods
- resilient to desiccation
- allowed movement onto land
- EPICUTICLE: made of proteins and wax- lightweight and waterproof
- EXOCUTICLE: tough pigmented tanned layer where cross links form
- MESOCUTICLE: protein and chitin bind to form glycoprotein
- EPIDERMIS: secretes the cuticle
in aquatic arthropods what can harden the cuticle?
ca salts
describe ecdysis in arthropods
shed old cuticle and grow a new one
- take up water/ air to make self bigger as cuticle hardens so new cuticle is bigger than body so can grow into it
- after each molt new features form, increasing weight of organism
what is the largest terrestrial and the largest aquatic arthropod?
terrestrial: coconut crab (50cm)
aquatic: giant spider crab (4m)
give 6 features of trilobites
- have 3 body regions (cephalon, thorax, pygidium)
- went extinct 250-270mya
- compound eyes made up of ommatidia- lens leading to pigment cells
- scavengers and filter feeders
- 2 branched limbs
- most trilobites outlasted by sea scorpions
when did sea scorpions go extinct and what are the 2 main regions?
extinct 250mya
prosoma and opisthosoma
describe the main 2 tagmata of chelicerates
- prosoma (cephalothorax)
- 6 pairs appendages
- chelicerae (pair of appendages at front of mouth, pincer like claws) - opisthosoma (abdomen)
- no distinct head and no antennae
describe the marine chelicerate of a horseshoe crab
- simple eyes used to detect opposite sex
- gnathobase grinds up food
- book gills used for respiration and are filled with blood and sea water and gas exchange occurs
- chela of third walking leg gathers food
- larvae develop in sediment
- haemocyanin in blood
- amoebocytes function like white blood cells
what are terrestrial chelicerates known as?
arachnids
give 6 features of scorpions
- mostly carnivorous (often use neurotoxins on prey)
- earliest group of chelicerates
- grab prey with chelicera
- use pedipalps in mating (male grabs female, drops spermatophore and leads her over it)
- females show parental care can live young can stay on her back for weeks
- telson and aculeus are stinging apparatus to inject venom
give features of spiders
- use pedipalps to mate
- chelicera form fangs which release neurotoxins
- small waist allows them to move their abdomen
- spin silk (made of protein fibroin) produced by silk glands and released from spinnerets to form webs
- can change consistency of silk
- can use silk for ballooning where it gets caught in the wind so can move
- can wrap food up and cocoon offspring
in arachnids what do the malpighian tubules do and where does gas exchange occur?
malpighian tubes are used in excretion to absorb useful substances and expel waste
gas exchange occurs at the book lungs and trachea deliver O2 to tissues
why is B.kiplingi spider different ?
it eats plant material- the beltian bodies of acacia bushes
what is the stabilimentum?
a structure on the web that could attract mates or prey or be to prevent birds flying into it
can spiders act cooperatively?
T.nigroannulatum is a cooperative spider species where they work together to capture larger prey using their silk
describe ticks and mites within chelicerates
ticks
- ectoparasites
- some can transmit disease such as lymes disease which affects the nervous system and can cause paralysis
mites
- free living and parasitic
- dust mites and their faeces have strong allergens affecting people
- varroa feeds on haemolymph of honey bee
give 4 features of pycnogonida
sea spiders
- abdomen very small
- 4 pairs legs
- reproductive structures carried outside body- males will carry the fertilised eggs
- ovigers are used to clean the legs
give 10 features of crustaceans
- predominantly marine but some occur in other in other environments
- malacostraca main group
- tagmatization and adaptive radiation of appendages
- compound eye
- pleopods can be used for swimming
- 2 pairs antennae
- 1-3 thoracic appendages may be incorporated into head (maxillipeds)
- appendages biramous
- filamentous branch can be enclosed to become a gill
- legs have protopod and endopod as main 2 sections
describe 5 features of the brine shrimp crustacean
- basic paddle like appendages moving in metachronal waves
- legs can be used to capture food and respire
- in salt lakes
- modified pleopod forms chelae
- abdominal region is used for swimming
describe crustacean daphnia
- animal enclosed in a carapace which can open to allow water in
- legs for food gathering and respiration
- 2 pairs antennae, second pair well developed and used to swim
- single compound eye
- undergo parthenogenesis but in harsh conditions can reproduce sexually
what is parthenogenesis?
reproduction from ovum without fertilisation
describe crustacean barnacles
- heads can be cemented to shell
- simple body, mainly thorax
- no abdomen
- hermaphrodite
- largest penis to body ratio in animal kingdom
- goose barnacle
- parasitic barnacle sacculina which latches onto crab growing into it and can feminise males by attacking their adrenal glands
what is the larvae of crustaceans?
nauplius larva
within myriapods there are centipedes and millipedes, describe both
centipedes
- head and trunk
- dorso ventrally flattened with legs out of sides
- well developed poison claw/maxilliped
- predaceous
millipedes
- head and trunk region
- spherical body with legs on it
- move quickly
- each segment has 2 pairs of legs
- feed on plant material so no poison claw
- emit hydrogen cyanide gas and other chemicals from repugnatorial glands
- movement of air by muscles and diffusion
- can lose water through spiracles
- substances drawn into malpighian tubules from haemolymph
what are the 3 tagmata in insects and what is found on the central one?
head, thorax, abdomen
thorax: 3 pairs legs and 2 pairs of wings
what is the current hypothesis for the relationship among the 4 living subphyla of arthropoda?
chelicerata grouped with myriapoda and crustacea grouped with hexapoda
give features of nematodes
- pseudocoelomate
- cuticle of collagen and cross links between the proteins make it tough and flexible
- 4 moults
- lots of pressure in the body
- epidermal layer secretes the cuticle
- largest over 8m in sperm whale placenta
- mostly dioecious
- internal fertilisation
- strong muscles at entrance and exit
- nerve chords run down from body from simple brain
- females larger and sex is environmentally determined
describe c.elegans (nematode)
- free living
- roughly 1mm
- hermaphrodite
- cells fate fixed early in development
- set number of cells on body
- first invertebrate genome sequenced
describe the genes for enhanced longevity in nematodes
pha-4 is linked to enhanced longevity on restricted diet
- if gene blocked no enhanced longevity
- if overexpressed then longevity even longer
describe parasitic nematodes and give 1 example
- parasitism evolved several times in nematodes
- radiation accompanied evolution of flowering plants, insects, amniotic vertebrates
- parasitic as juveniles, adults or both
- one or more intermediate lost
- root knot nematode infects plants so crop yield and economy decreases and the nematode drains nutrients and photosynthetic products of plants
describe the parasitic behaviours of:
a) s.morrisoni
b) m.neotropicum
a) infects amphipod meaning they swim to surface of water in daylight, birds more likely to feed on them
b) ant infected with nematode causes abdomen to swell and become red- attractive for birds to feed
describe life cycle of a pinworm
indirect/ only in human cycle
- eggs enter host by ingestion
- eggs hatch in intestine
- larvae mature
- pinworm in human gut
- impregnated female migrates to hosts anal region at night
- zygotes released on host, bedclothes into airborne dust
describe life cycle of hookworm
penetrates human skin and scrapes intestine
- eggs develops in soil
- rhabditiform larva hatches
- larvae molts
- penetrates human skin
- larvae enter circulatory system
- heart
- lungs
- trachea
- larvae enter esophagus and is swallowed
- larvae matures in intestine
- hookworm adult in human intestine
- fertilised eggs released in faeces
what are asceroids?
- larger nematodes
- up to 50cm
- indirect life cycle
- lots of them so can block gut
what is the guinea worm (parasitic nematode) lifecycle?
- live in subcutaneous tissue
- form an ulcer
- water touches it and larvae are released
- larvae released into copepod which is the intermediate host
- taken up in drinking water
- penetrate gut and lodge into subcutaneous tissue
what’s an example of the filarial nematodes?
W.bancrofti
- adults inhabit lymphatic glands
- intermediate host
- elephantiasis occurs (severe swelling of arms legs and genitals)
1. mosquito bites
2. adults in lymphatica
3. adults microfilariae migrate into lymph and blood channels
4. mosquito bites
5. microfilariae penetrate mosquitos midgut and thoracic muscles
6. migrate to head and mosquito’s proboscis
whats the benefit of symbiosis in nematodes?
most nematodes form symbiotic relationships with bacteria meaning works can be treated with antibiotics as they kill bothe the worm and the bacteria
give 7 features of echinoderms
- pentamerous radial symmetry
- body divided into 5 parts
- not related to other radially symmetrical groups
- 3 body layers
- coelom
- larvae bilaterally symmetrical
- larvae show convergent evolution with other larvae even though not closely related to them
whats the outer structure of echinoderms?
have an internal skeleton of ossicles
- each ossicle caco3 has crystal structure separated by living tissue
- ossicles can fuse to form a test (hinged hard outer casing)
- some ossicles are minute/absent such as in sea cucumbers
whats the purpose of tube feet/podia?
large= locomotion and feeding small= respiration and suspension feeding
describe the water vascular system of echinoderms
helps operate the podia
- tiedemanns can ingest waste material
- contains canals full of fluid which go down each of the legs
- water flows between ampulla and podium (suction cup at the end)
- sea urchins have suction cup at the podium for grip
- others have chemical reaction occur for grip
what is mutable connective tissue?
- it can alter rigidity
- under nervous control
- due to changes in fluidity of collagen fibres in connective tissue
- can eject organs to deter predators, these can be regenerated
give 11 features of asteroidea
- pedicellariae: jaw like and remove waste that may accumulate
- ambulacral ridge is where the podia are found
- mouth on underside oral side
- papula is for gas exchange and excretion
- sophisticated nerve net
- control comes from radial nerves connected to nerve junction
- connection at nerve junction important to podia to travel in same direction
- local control can occur so parts can temporarily function as brain
- if cut some arms will continue in theri direction but others wont know which direction to follow
- short arms may swallow food whole
- long arms can grab prey such as prying apart mussels and eject stomach to digest externally
give 10 features of ophiuroidea
brittle stars
- photosensitive
- no ambulacral groove or ampullae
- podia not used in locomotion but are feeding
- bursal sites: respiration
- feed: scavenging, deposit feeding, suspension feeding
- ossicles form plates over body
- mucus on podia allow it to catch prey
- can change colour due to chromatophores in skin
- radial nerves with ganglia
- legs and spines can grip substrate
give 3 features of echinoidea
sea urchins
- spines and podia used for movement
- ossicles fuse to form test
- aristotle’s lantern made ossicles and forms a chewing device when feeding on rocks and larvae
gives features of holothuroidea
- ossicles very small
- bilaterally symmetrical pattern but podia in a radial pattern
- crown of 10 dendritic tentacles (modified podia)
- deposit and suspension feeders
- podia used crawling/gripping
- attached or irritated tubules from anus and toxin (holothurin)
- anus leads to canals for respiration at respiratory tree
give 8 features of crinoidea
sea lilies and feather stars
- mouth on top
- most ancient group
- free living
- can move by waving arms
- ossicles present at calyx
- ciliated ambulacral groove
- sea lilies use arms to feed and are in the deep sea
- feather stars are free living and use their arms to move and swim, suspension feeders
give 3 features of hemichordates
- coelomates
- half chordates
- 2 main groups include enteropneusta and pterobranchs
