Echinoderms (Echinoidea)

Question 1

Regularia features and representatives

Answer 1

radial symmetry

sea urchins

Question 2

Iregularia features and representatives

Answer 2

secondary bilateral symmetry

heart urchins, sand dollars, sea biscuits

Question 3

endoskelleton (urchins)

Answer 3

test

expanded oral surface

Question 4

repro (urchins)

Answer 4

broadcast spawners

genital plates with gonopores

Question 5

complex grazing mouth (urchins)

Answer 5

Aristotle’s lantern

40 skeletal pieces!

teeth harder than the rest of skeleton

teeth secreted from internal sacks at rate of 1mm/week

Question 6

locomotion (urchins)

Answer 6

spines, tube feet

spines mounted on ball joint (“boss”) with muscles around

spines can be used to burrow into soft rock or coral

Question 7

growth (urchins)

Answer 7

growth on outside only, growth lines visible on inside of plates

new plates added on aboral surface

test growth is highly regulated/precise

muscles control reshaping of curve as plates grow

guessing age: # of plates from mouth to anus, growth rings on inside of plates

Question 8

sand dollar

Answer 8

anus on edge

burrowers

sometimes “stand up” to collect food particles

Question 9

heart urchins-

sea buiscuits-

Answer 9

• kinda fat ostracod shaped

- like sand dollars but puffy