Animal biodiversity 3 - invertebrates Flashcards
what are the 3 defining features of the phylum mollusca?
1) muscular foot for locomotion
2) visceral mass containing internal organs
3) mantle - fold of tissue covering the visceral mass
what are the 3 classes within the phylum mollusca?
1) gastropoda
2) bivalvia
3) cephalopoda
what does gastropoda include?
snails. limpets, slugs
what does the mantle cavity serve as in terrestrial snails?
lungs allowing them to breathe
how do gastropoda move?
rippling motion of foot or by cilia
what is the radula used for?
to graze on algae or bore holes in shells of prey
what is torsion?
during development the visceral mass rotates 180 degrees moving male cavity(anus) over head
how does the process of torsion take place and why might it be useful?
- retractor muscles on right side grow earlier than on left hand side so it moves -possible balance aid or safety from predators
what are in the group bivalvia?
clams and oysters
describe the shell of bivalvia?
divided into 2 halves - hinged at mid dorsal line
where are the body and foot located in bivalvia and what is the foots use?
flattened inside the shell - foot used for digging or anchoring
how do bilvalvvia feed?
they have gills adapted for filter feeding and gas exchange
why are the head and radula (teeth) lost in bilvalvia?
because they have a sedentary lifestyle
what are in the group cephalopods?
sqiuds and octopus
in cephalopods what is the foot like?
modified into a siphon for propulsion or tentacles for feeding
what is the cephalopods circulatory system?
3 hearts with blood blood due to high levels of copper
3 features of cephalopods
1) complicated eye design with no blind spot
2) chromotophores which change colour for camouflage
3) well developed CNS and brain
which of the 3 groups is most successful in terms of species diversity
gastropods
what is the main feature of ecdysozoas giving them their name?
ecdysis- the shedding of their exoskeletons allowing them to grow in size
what are the 2 groups of ecdysozoas?
1) Nematoda - round worms
2) Anthropoda - lobsters, spiders, insects
what is a pseudocoel?
body cavity which is not the production of gastrulation
what is the job of the pseudocoel and cuticle in nematoda?
act as hydrostatic skeleton
what is nematoda reproductive strategy?
sexual reproduction with internal fertilisation
what are 3 features of anthropoda body structure?
1) hard jointed exoskeleton or cuticle made of chitin an protein
2) segments fused in groups forming regions called tagma
3) appendages for specialised functions allowing efficient body plans
3 features of anthropoda internal system?
1) open circulatory system - organs bathed in fluid
2) 3 guts
3) dorsal heart
what are the 4 potential origins of insect wings?
- heat absorption in terrestrial ancestor
- gliding from vegetation to ground
- gills in aquatic ancestor
- swimming fins in aquatic ancestor
what are the 5 anthropod sub groups?
1) trilobites (extinct)
2) Chelicerates ( spiders, ticks, horseshoe crabs)
3) crustacea ( lobsters and crabs)
4) Uniramia hexapods (insects )
5) chilopoda/diplopoda (millipedes and centipedes)
what is a cephalothorax?
fused head and thorax
what is the difference between the 4 of the anthropoid sub groups body sections?
trilobites - loads of segments not grouped together
Chelicerates - cephalothorax and abdomen
crustacea - head, thorax, segmented abdomen (3 mouth part appendages)
chilopoda/diplopoda - loads of little segments - paired segments are fused
hexapoda -3 sections: head thorax and abdomen
how do insects carry out gas exchange?
well developed traheal system in which tubes lead to every cell in the body, spiracles regulate air flow and water loss
how do cephalopods hunt?
they are active predators which use their tentacles to grasp prey and their beak like jaws inject an immobilising poison
what is the difference between nematoda and annelids?
nematodes do not have a segmented body
3 features of nematodes?
1) coelom not fully bound by mesoderm
2) cuticle shed during growth
3) lacks circulatory system nutrients transported via fluid in pseudocoel
what was the result of the evolutionary changes of arthropods?
great diversification and efficient body plan that permits the division of labour among different regions
3 important features of class insecta
1) sophisticated sensory organs including complex eye
2) well developed nervous system, allows complex behaviour
3) one or two pairs of wings derived from cuticle out-folding
which arthropod group has the most sub species?
hexapoda
