lab/lecture 14 echinodermata

Question 1

Describe (Phylum) Echinodermata.

Answer 1

Marine animals with pentameral symmetry (fivefold), a water vascular system, calcareous skeleton (stereom), tube feet; includes starfish, sea urchins, crinoids.

Question 2

Describe stereom.

Answer 2

Unique porous calcite making up echinoderm skeletons; plates called ossicles form the rigid or flexible body framework.

Question 3

Describe the water vascular system.

Answer 3

Hydraulic system of canals and tube feet for movement, feeding, respiration; water enters via madreporite, flows through stone canal, ring canal, radial canals.

Question 4

Describe (Class) Crinoidea.

Answer 4

Sea lilies; stalked echinoderms with cup-like calyx, arms with pinnules, filter feeders; dominant Paleozoic benthos; stalk made of ossicles called columnals.

Question 5

Describe (Class) Blastoidea.

Answer 5

Extinct stalked echinoderms (Ordovician–Permian); had theca with spiracles, hydrospires, thin brachioles for food gathering; similar to crinoids but no tube feet.

Question 6

Describe (Class) Echinoidea.

Answer 6

Sea urchins, sand dollars; rigid test of fused plates, spines for movement/defense; regular forms epifaunal, irregular forms burrow and have bilateral symmetry.

Question 7

Describe (Class) Asteroidea.

Answer 7

Starfish; five or more arms, coelomic extensions, tube feet, predatory; stomach can evert to digest prey like bivalves.

Question 8

Describe (Class) Ophiuroidea.

Answer 8

Brittle stars; five slender arms without coelomic extensions, central disk, feed on detritus or suspended particles.

Question 9

Describe (Class) Holothuroidea.

Answer 9

Sea cucumbers; elongated body, reduced skeleton as spicules, pentameral symmetry along body axis; suspension or deposit feeders; can eject organs for defense.

Question 10

Describe (Class) Helicoplacoidea.

Answer 10

Early Cambrian, spiral-plated echinoderms with three ambulacra; adapted to firm, microbial sediments.

Question 11

Describe (Class) Eocrinoidea.

Answer 11

Early stalked echinoderms (Cambrian–Silurian); common Cambrian fossils, paraphyletic group.

Question 12

Describe (Class) Edrioasteroidea.

Answer 12

Disk-shaped echinoderms (Cambrian–Carboniferous) with five ambulacra; attached to hard surfaces, often brachiopods.

Question 13

Describe regular vs. irregular echinoids.

Answer 13

Regular: radial symmetry, surface-dwelling, use Aristotle’s lantern; irregular: secondarily bilateral, burrowing, reduced spines.

Question 14

What functions do echinoderm tube feet serve?

Answer 14

Locomotion, feeding, respiration; extend/retract using ampullae.