Invertebrates 1 Flashcards
metazoans are thought to have originated from a … … approximately …MYA
colonial flagellate, 700
- colonial theory - colonial single-celled organisms became interdependent on each other
- like volvox
Evidence for colonial flagellate theory:
- flagellated cells found in metazoans (sponges, sperm cells)
- many flagellates form colonies (e.g. volvox)
- molecular evidence (developmental genes associated with groups of colonial flagellates)
Likely ancestors were something like the …
choanoflagellates
The sponges are found in the phylum …
Porifera
- simple structure
- successful and widespread
- ancient group of animals
Sponge cells are …
totipotent
Most sponges are … but a few are …
marine, freshwater
Sponges are effectively …
sessile
Sponges tend to be … and … in more fast-moving waters
smaller, flatter
The hole at the top of a sponge where water leaves is called the …. The small pores through which water enters are called …. The calcareous fibres that form the structure of the sponge are called …. The water moves by means of flagellated cells called …, which trap food items. The hollow centre of the sponge is called the …
osculum, ostia (through porocyte cells), spicules, choanocytes, spongocoel
Water passes through sponges at up to … times its volume in 24 hours
20,000
Glass sponges - 75% of tissues are …. Signals are transmitted using … …, despite having no nerve cells
syncitial, electrical impulses
Most sponges are … feeders but some are …
filter, carnivorous (e.g. heart sponge)
Sponges help … … thrive in ocean deserts
coral reefs
- sponges take up carbon produced, releasing it for consumption by other organisms in reef
- recycling nutrients
Larger sponges have more … to increase SA
infolding
- more ostia and oscula
Sponges are remarkably able to …
regenerate
- when passed through sieve
- separate into separate species when sieved
Sponges reproduce … or …
asexually (by budding or by gemmules), sexually
Sponge amoebocytes are …
totipotent
Some sponges produce … - some have antibacterial activity
biotoxins
Bilateral symmetry often implies an … …
active lifestyle
Eumetazoa divided into…
radiata and bilateria
Bilateria divided into…
protostomia and deuterostomia
Cnidaria have … body layers and limited … development
two
- epidermis and gastrodermis - mesoglea between
organ
cnidaria exist in 2 forms: … and …
polyp (sessile), medusa (free-swimming)
Food taken in and waste excreted from same opening: …
mouth - might have lost anus rather than other animals gaining one
in cnidaria, … cells are totipotent
interstitial
Nematocysts, when stimulated … or …, inject … …
mechanically, chemically, protein toxin
How do carnivorous cnidarians eat
prey -> tentacles -> mouth (lots of mucus) -> gastrovascular cavity -> digested and taken up by nutritive muscle cells
What are the different groups of cnidarians?
Hydrozoa, scyphozoa, cubozoa, anthozoa
Hydrozoa are usually … and often show secondary …
colonial, polymorphism (e.g. showing polyp and medusa form during life cycle)
Hydra has no … …
larval stage
EO Wilson says the … are one of the 4 pinnacles of … evolution
siphonophores (e.g. portuguese man o war), social
In scyphozoa, the largest tentacles, associated with feeding, are called … …
oral arms
box jellyfish are more … … and will actively … their prey. They have 24 … …
active swimmers (rather than drifting - can swim at 2m/s), pursue, complex prey
In anthozoans the … stage is absent
medusa
Anthozoans have muscular … which increase SA and fill their chambers with water to act as a … …
septa, hydrostatic skeleton
Anthozoans reproduce…
asexually by pedal laceration and longitudinal fission, and sexually by fertilisation in gastrovascular cavity or sea, forming planula larvae - usually hermaphrodites but function as one sex at a time
Anthozoans are often found in … relationships
symbiotic, e.g. anemones and clownfish (more stripes on clownfish = more toxic anemone)
Corals have a skeleton of … … and build reefs. They contain … (algae) in their gastrodermis
calcium carbonate, zooanthellae (essential to formation of skeleton - coral bleaching caused by zooanthellae leaving coral)
What 2 groups are the protostomes divided into?
lophotrochozoa and ecdysozoa
The platyhelminthes are the…
flatworms
What are thought to be the basal bilateria group?
Xenacoelomorpha
Platyhelminthes are triploblastic (…), … symmetrical animals with pronounced … and … development. They are … flattened
acoelomate, bilaterally, cephalisation, organ, dorsoventrally (for SA:V ratio)
cephalisation means…
a concentration of nervous tissue at the anterior end
Platyhelminthes have a gut with … … and a simple excretory system (…)
one opening, protonephridia
Platyhelminthes have simple … … and are negatively …. They have … associated with chemical detection.
phototrophic (to avoid dessication), auricles
Platyhelminth pharynx can be…
inserted into food
Flatworms are able to … according to a gradient (use concentration differences
regenerate
Thompson and McConnell (in 50s and 60s) suggested … could be transferred … (in flatworms) but results have never been reproduced
memory, chemically
light + electric shock conditioning
Flatworms often display … … behaviour to avoid having to look after eggs (and act as a female after copulation)
penis fencing
Which flatworm is considered a pest in the UK
New Zealand Flatworm - feeds on earthworms
What are some adaptations often found in parasitic organisms?
- loss of unwanted organs (or reduced)
- penetration devices
- attachment devices
- protective devices
- transmission via a vector
- production of eggs etc in large numbers
Trematode worms are called …
flukes
Fluke features include…
- non-ciliated syncytium (tegument)
- suckers (oral and ventral)
- reproduce 10,000 to 100,000 times more eggs than free-living flatworms
- hermaphrodite (usually) and mutual copulation
- complicated life cycles (sexual and asexual stages, intermediate hosts)
Blood flukes give rise to…
schistosomiasis
- not hermaphrodite
- kills 200,000 a year (mainly due to diarrhoea)
People infected by flukes show reduced … …
allergic reactions
Diplostomum spathaceum causes … in the eyes of fish, making them easier to catch by seabirds, their final host
cataracts
- at worst when at most infectious stage
Lancet flukes develop in snails, released and fed in by ants, which control … … of ants, making them climb … grass and clamp during the day, so they are eaten by sheep
nervous system, up
Tapeworms (cestoidea) have no …, a … allowing it to attach to its host, and segments called … containing reproductive tissues
gut, scolex, proglottids
Tapeworms form a … stage in the muscle
bladderworm
Tapeworms are able to …-… if there is no mate nearby
self-fertilise
The annelids are … animals
coelomate
What are the advantages of a coelom
- transport
- gut moves independently of body wall
- site for gamete maturation
- hydrostatic skeleton
Water can act as a base against which…
muscles cab contract
When the circular muscles contract, the animal becomes … and …, and when the longitudinal muscles contract, the animal becomes … and …. This allows the movement of the animal (…)
long and thin, short and fat, peristalsis
Annelids show … segmentation. All segments are repeated except the head (…) and tail (…) segments. New segments are formed near the ..
metameric, prosromium, pugidium, pigidium
In annelids, the … runs through the entire animal. The … are found in each individual segment
gut (+ nerve cord and blood vessels), nephridia
Segmentation may be modified by…
- restriction of structures to particular segments
- some segments develop special structures
- segments may fuse together
Clitellata have a …
clitellum
Polychaetes are not …, whereas clitellata are.
hermaphrodites
polychaetes are dioecious
Polychaetes have fleshy projections called … and well-developed …
parapodia (with setae)
- highly vascularised, for gaseous exchange
heads
setae help to …
burrow and help with movement
Polychaetes can be sedentary (often filter feeders) or …
errant (often predators)
Polychaete fertilisation occurs ..
externally - spawning may be synchronous
Polychaete larva is
trochophore form larva
Clitellata have no …, and produce … and …. They have … restricted to a few segments
parapodia, clitellum, cocoons, gonads
Oligochaetes have few … and … locomotion
setae, peristaltic
Earthworms keep their body moist for gaseous exchange with …
mucus
- earthworms come closer to surface when it is wet
Earthworms pull leaves into their burrows from the … …
narrowest point - so have some intelligence
Earthworms reproduce with mutual … …
sperm transfer (male gonopore to spermathecal opening) -> passes over female gonopore which releases eggs - bound tegether by mucus
Hirudineans have no … and are restricted to … segments. They also reproduce by mutual sperm transfer. … between segments are completely broken down. Reduced … due to mode of transport using suckerson both ends instead
setae, 34, septa, coelom
blood sucking leeches produce …-… and …
anti-coagulant (hirudin) and anaesthetic
can feed on 10 times their body weight in blood and use symbiotic bacteria to help breakdown after absorbing water.
The molluscs are the…
second largest group of animals after the arthropods
Molluscs are … animals
coelomate
Molluscs have a … larval stage, which have a … of …
trochophore, band, cilia
What is the mass of organs above the foot of a mollusc called?
visceral mass
The visceral mass is covered by the …, which secretes the …
mantle, shell (not all have shell)
Under the mantle is the mantle …, which houses the …
cavity, gills
What is the feeding device of a mollusc called?
radula
- “conveyor belt” of grinding chitinous teeth
What surrounds the gut of a mollusc?
Nerve ring
Molluscs have … … circulatory system
an open
- with haemocoel
Which group of molluscs is the most species diverse?
gastropods
Gastropods have development of a … with a … for feeding, …-… … of the body, a … which acts as a shield or protective retreat, and display … (rotation of visceral mass and mantle cavity through 180 degrees)
head, radula, dorso-ventral, shell, torsion
+ often spiralling of visceral mass
In gastropods, what is the next larval stage after the trochophore stage?
veliger larva - where torsion takes place
What are the ideas for the advantages of torsion?
- Protection of veliger larva (although studies show certain animals prefer post-torted prey - not strong evidence)
- protection of adult (from predation or dessication)
- Utilisation of oncoming water by gills (aids in aeration of gills
What are the disadvantages of torsion in gastropods?
Anus over head (faecal matter mixed with food potentially)
Abalone and keyhole limpets have managed the problem of torsion with…
holes in their shells which allow water to pass over their gills and also to remove waste from their anus
Gastropods that have undergone de-torsion include…
nudibranchs (sea slugs) - have reduced or lost mantle cavity and gills in the cavity, instead having external body projections functioning as gills
- nematocysts and bright colours to protect as have no shell
- sea hare produces ink and opaline which interferes with antennae of crustacean predators
Rather than being planospiral (symmetrical), most spiral shelled gastropods have shells that are…
conispiral (asymmetrical)
- easier to balance (not so top-heavy) and fit into small spaces - although means visceral mass may be restricted on one side
In snails, single recessive gene responsible for…
opposite spiralling
- interested as may be responsible to similar opposite organs thing in humans
Pulmonates are the …-dwelling gastropods, including … and …, and instead of gills they have a … mantle cavity, which acts like a …
land, snails, slugs, vascularised, lung
What is the story of the viviparous Partula snail of tahiti?
Pest species African land snail (which feeds on crops) - introduced rosy wolfsnail as biological control but fed on partula instead of African land snail and wiped out species for the most part - now programmes to try and conserve
Which muscles do bivalves use to keep their shells closed?
adductor muscles
Bivalve heads and nervous systems are…
very reduced
Bivalves don’t have a radula for feeding. Instead they can use their…
foot (primitive bivalves called protobranchs which are deposit feeders) or their gills (lamellibranchs - filter feeders)
Most bivalves are…
dioecious
What do mussels use to attach themselves to rocks?
Byssus threads
- also may be used as defence against predators
Clams have hundreds of … around their mantle cavity
eyes
- only detect changes in light
Cephalopods have a change in the … of the body and have their foot modified into …
orientation, tentacles
instead of cilia, cephalopods use … … to pass water over their gills in their mantle cavity
muscular action
Cephalopods can use jet propulsion to move by..
rapidly expelling water out of their exhalant siphon
Cephalopods are dioecious and often males present the female with a …
spermatophore
Cephalopods have enhanced … and well-developed …
cephalisation, brains
Cephalopods have a beak with a … and some produce a … e.g. blue-ringed octopus
radula, neurotoxin
What do cephalopods have that allow them to change colour?
chromatophores controlled by muscular action
Cephalopods also have a … circulatory system with … hearts which pump deoxygenated blood into the gills
closed, accessory
The nautilus is the only..
fully shelled cephalopod mollusc
The nautilus sits in the … chamber of its shell
final
In what ways are nautilus simpler than other cephalopods
simpler eyes, cant change colour, dont produce ink
Why do nautilus have shells?
it is a buoyancy device - salt can be pumped or removed from siphuncle in shell to draw into or release water from the region in order to adjust buoyancy
Cuttlefish have an internal …, squids have a shell reduced to a proteinaceous …, octopuses have a … or … shell
shell (cuttlebone - also used to adjust buoyancy), pen, vestigial, absent
How do squids adjust buoyancy?
Controls amount of ammonia in body
