Echinoderms

In deuterostomes, the blastopore becomes the anus.

nervous system is on the dorsal side

stationary

• calcareous ossicles- made of calcium carbonate
• mesodermal
• bound together with connective tissue

Ossicles are small calcareous elements embedded in the dermis of the body wall of echinoderms. They form part of the endoskeleton and provide rigidity and protection.

locomotion, madreporite, tube feet

5 limbs off a central disk

• found in the ambulacral groove on the oral surface
• filled with fluid
• it has retractor muscles

• opens and closes
• sieve in endoskeleton for water input into water vascular system

cental disk

branches of ring canal in starfish

connects all tube feet

where respiration occurs

• mini claws
• remove debris around papulae
• sometimes used in capturing food
• keeps papulae clean so they can respire efficiently

disk in the middle and the radiating arms

side containing mouth is the oral surface and the other side is the aboral surface

complex mouth part in echinoidea (sea urchins and sand dollars)

shell that encloses internal organs and its made of calcium carbonate

modified tube feet in holothuroidea (sea cucumbers) surrounding the mouth