zoology week 4

Question 1

Deuterostomia

Answer 1

3rd super phylum: radial indeterminate cleavage, anus forms from blastopore, coelom derives from endoderm outgrowths (enterocoelus), mesoderm derives from ectoderm

Question 2

Protostomia

Answer 2

spiral determinate cleave, mouth forms from blastopore, coelom derives from mesoderm (schizocoelus)

Question 3

Ambulacraria

Answer 3

clade containing echinodermata and hemichordata

Question 4

Echinodermata

Answer 4

phylum within deuterostomia: pentaradial symmetry, skeleton made from ossicles, coelom derives water vascular system (madreporite) and hemal system, tube feet controlled by ampullae
Have planktonic larvae (often used in experiments in place of chordates) and external fertilisation

Question 5

Asteroidea

Answer 5

Echinoderm class: Starfish: legs originate from central point which has a nerve ring, tube feet used for locomotion, eversible stomach for predatory feeding, partial regeneration, oral opening facing down, madreporite on aboral surface

Question 6

Ophiuroidea

Answer 6

Echinoderm class: brittle and basket stars: sharply defined central disc, tube feet do not have ampullae, water vascular system not used for locomotion (coelom confined to central disc), madreporite on oral surface (facing down), simple stomach and no intestine or anus (waste goes out mouth)

Question 7

Echinoidea

Answer 7

Echinoderm class: sea urchins: ossicles for rounded test with openings for spines and tube feet, tube feet and spines used for locomotion, large coelom and Aristotle’s lantern for feeding

Question 8

Holothuroidea

Answer 8

Echinoderm class: sea pigs and cucumbers: elongated along aboral axis (ventral side down), modified tube feet around mouth (tentacles), locomotion through tube feet and worm-like contractions of the body wall
use a respiratory tree (branched tube system close to anus) to draw water in and out of anus to breath, this is also pushed out as a defence mechanism

Question 9

Crinoidea

Answer 9

Echinoderm class: sea lilies: have a stem made of stacked ossicles, mostly sessile, anus faces up (same surface as mouth) feather stars: crawl/swim (no stems), filter feed with limbs, only class that has primitive brain (nerve cluster) instead of a nerve ring

Question 10

Hemichordata

Answer 10

Deuterostome phylum: dorsal nerve chord and ciliated pharyngeal slits (similar to chordates), live in or on marine sediments, 2 body regions (proboscis, collar and trunk), tripartite coelom (three parts)