Echinodermata

Echinoderms are sea-dwelling, coelomates with body parts radiate from the center with the exception of echinoderm larva - which are bilateral.  These deuterostomes have a water vascular system that is a network of canals branching into tube feet.  Tube feet are the suction-cup looking appendages on the bottom of a starfish that function in feeding, movement and gas exchange.  During reproduction echinoderms release male and female germ cells into the water.

Asteroidea (sea star) have five or more arms and tube feet to anchor and hunt.  When one gets ahold of a clam it turns its mouth inside-out to insert digestive fluids into the clam's shell.

Ophiuroidea (brittle stars) have long slender flexible arms but no suckers on their tube feet.  They move more by lashing or whipping their thin arms.

Echinoidea (sea urchin, sand dollar) have five rows of tube feet.

Crinoidea (sea lily).  Some are sessile, some can crawl.  Sea lilies are mainly suspension feeders, filtering food from the water.  The arms encircle the mouth.

Holothuroidea (sea cucumber) have five rows of tube feet with the tube feet around the mouth being more specialized than the others.  Sea cucumbers obviously (because they are shaped like cucumbers) have an oral-aboral (mouth-anus) elongation.

Concentricycloidea (sea daisies).

What do Chordates have in common with Echinoderms?

1. radial cleavage.
2. a coelom from the archenteron.
3. the blastopore becomes the anus.

Next:  "Animals: Chordates."