Animal biodiversity 2 - invertebrates Flashcards
what is the simplest most primitive animals?
phylum porifera - sponges
what are 4 features of the parazoa?
1) no gastrulation
2) no true tissues
3) some specialised cells
4) lack muscles/nervous system/organs
describe the reproductive strategy of sponges
reproduce sexually as hermaphrodites. fertilisation occurs in the mesohyl as sperm are carried out by current, flagellated zygotes settle on suitable substrate
what is the next group up from the metazoan and what phylum does that include?
the eumetazoa (radiata) including phylum cnidaria (jellyfish)
what are the 2 types of eumetazoa?
1) sessile polyp (mouth up)
2) floating medusa (mouth down)
what symmetry and how many embryonic layers do eumetazoas have?
radial symmetry and diploblastic (2 layers)
what are 3 features of cnidaria?
1) no brain
2) simple nervous system
3) mouth and anus are the same gastrovascular cavity
what are they feeding habits of eumetazoas?
they are carnivores which catch their prey by tentacles piercing prey and releasing venom
what are the 4 groups of eumetazoas and their forms?
1) hydrozoan - regenerate alternating between polyp and medusa form
2) scyphozoan - medusa stage is predominant
3) cubozoan - medusa stage
4) anthozoan - polyps
what are the 2 groups of the protostomia?
- Lophotrochozoa
- Ecdysozoa
what are 2 features of protostomes?
1) characteristic cell division and coelom formation, early cell determination and mouth forms first
2) ventral nerve cord
what forms first in protostomes?
the mouth
what is the phylum platyhelminthes?
flat worms
do flat worms have a coelom?
no it is believed they used to have one but lost it in evolution
how many tissue layers do platyhelminthes have?
3 triploblastic
what are 3 features of lopotrochozoa?
1) mesoderm contains true organs and muscles
2) sensory/motor development
3) lack gas exchange and circulatory organs
what are the 5 reasons the evolution of a well developed coelom is so important?
1) hydrostatic skeleton
2) body space for storage and organ development
3) cushion for organs
4) buffers body wall muscle actions from muscles in digestive tract
5) allows for specialisation of regions of the body
what is the problem with the new zealand flatworm and what are its predators?
they were imported by accident and eat earth worms which are good for the soil, ground beetle larvae eat them
what are trematoda and what is their lifecycle?
parasitic flukes which lifecycle involves intermediate hosts
what is the lifecycle of cestoidea (parasitic tape worms)
they attach to primary hosts intestines and reproduces
what is the phylum Annelidia and 3 features?
segmented worms
1) blood vessels in closed circulatory system
2) coelom divided by septa
3) digestive tract has specialised regions
how do earth worms reproduce?
hermaphrodites which cross fertilise but can also reproduce asexually by fragmentation
what is the body structure of leeches?
dorsally flattened, reduced segmentation and coelom
define an invertebrate
animals that lack a backbone
how do sponges feed?
suspension feeders - capture food particles suspended in water drawn through the spongocoel and flows out osculum
what are choanocytes?
collar cells with flagella that generate water current and trap food which line the spongeocoel
4 features of class turbellaria
1) regenerate or reproduce sexually
2) hermaphrodites
3) eyespots detect light
4) gastrovascular cavity with complex folding
what are 3 classes of annelids?
1) earthworms
2) marine segmented worms
3) leeches
which has more sub species platyhelminthes or annelids?
platyhelminthes
