| Question |
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| Answer |
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| Six characteristics that define an animal |
1. multicellular, heterotrophic
2. usually use sexual reproduction
3. no cell walls
4. motile for at least part of life
5. rapid response to external stimuli
6. diploid is dominant ploidy |
| blastocoel |
cavity inside blastula |
| gastrula |
fold in blastula due to gastrulation |
| blastopore |
opening to pouch/archenteron |
| archenteron |
internal cavity of gastrula |
| ectoderm |
outer germ layer becomes skin and nervous tissue |
| endoderm |
inner germ layer becomes digestive tract |
| mesoderm |
middle germ layer becomes muscles and internal organs. primitive animals dont have this |
| lines of evidence that animals evolved from chanoflagellates (colonial protists) |
1. similarity in cells of choanoflagellates and sponges
2. choanocytes identified in other animal phyla but not in protists
3. DNA |
| Edicarian |
x |
| Cambrian Explosion which phyla appeared (5) |
Echinoderms, chordates, porifera, cnidaria, arthropoda. Hard bodies evolved in response to predation.
|
| define cephalization |
concentration of neurons in one region |
| Which is the only diploblastic phylum? |
Cnidarians |
| Coelom |
body cavity for development of internal organs. it is lined by mesoderm |
| pseudocolomates |
body cavity but it is lined only on one side by mesoderm |
| name two pseudocoelomate phyla |
rotifera and nematoda |
| Protostome: type of cleavage? determinate or indeterminate growth? fate of blastopore? |
spiral, determinate, blastopore becomes mouth |
| Deuterostome: type of cleavage? determinate or indeterminate growth? fate of blastopore? |
radial cleavage, indeterminate, blastopore becomes anus |
| Points of agreement in animal systematics: (5) |
1. all animals share a common colonial flagellate (choanoflagellate) ancestor
2. sponges are basal (the lowest form)
3. emetazoa - clade includes all animals with true tissues
4. most animals are bilateral
5. deuterostomia
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| Bilateral animals split into three groups: |
deuterostomia, lophotrochozoa, echydsozoa |
| Define Lophotrochozoa |
have either a lophophore (apical tuft of feeding cilia) or larval stage called a trochophore |
| Define Ecydsozoa |
external skeletons that shed as they grow |
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