Echinoderms

Question 1

Orders of echinoderms?

Answer 1

Asteroids (starfish) 
Ophiuroids (brittle stars) 
Echinoids (sea urchins) 
Holothurians (sea cucumbers) 
Crinoids (sea lilies and feather stars)

Question 2

Features of echinoderms?

Answer 2

Pentaradial symmetry
Water vascular system
Endoskeleton
Marine

Question 3

What is a madreporite?

Answer 3

A perforated plate by which the entry of seawater into the vascular system of an echinoderm is controlled.

Question 4

What is aboral?

Answer 4

End furthest from the mouth.

Question 5

What does the water vascular system consist of?

Answer 5

A ring canal in the centre, radial canals radiating outwards with ampullae and tubefeet.

Question 6

Features of echinoderm endoskeleton?

Answer 6

Ossicles of calcium carbonate. Brittle stars have moveable arms due to thinner arms with flexibility between ossicles.

Question 7

Taxonomy of hemichordates?

Answer 7

Enteropneusts (acorn worms)

Pterobranchs

Question 8

Features of acorn worms?

Answer 8

Very fragile worms.

Few cm long and in a marine environment. Burrows in sand and mud.

Holes in pharynx - pharyngeal gill slits.

Nervous system with an epidermal nerve net.

Question 9

Features of pterobranchs?

Answer 9

Tiny (few mms). Sessile.

Sometimes live in colonies.

In a tube, on a stalk. U shaped gut. Filter feeders