| A | B |
|---|
| Echinodermata | Phylum of "spiny skins" |
| Chordates | Echinoderms may share a common ancestor with lower chordates |
| Larval symmetry | Free swimming, bilateral symmetrical larva |
| Adult symmetry | Bottom dwelling, radil symmetrical adults |
| Pentaradial symmetry | Five radii or multiples of 5 |
| Endoskeleton | Internal skeleton composed of calcium plates which may include protruding spines |
| Water-vascular system | A network of water filled canals |
| Tube feet | Numerous small, movable protrusions that aid in movement, feeding, respiration, and excretion |
| Circulatory system | None in echinoderms |
| Respiratory system | None in echinoderms |
| Excretory system | None in echinoderms |
| Nervous sytem | Nerves, but no head nor brain |
| Reproduction | Two sexes; can reproduce sexually or asexually |
| Sessile | Not free living, possible status of fossilized echinoderms |
| Five classes | Crinoidea, asteroidea, ophiuroidea, echinoidea, holothuroidea |
| Parthenogenesis | Reproduction of organisms without the fusion of gametes of the opposite sexes |
| A rigid, compact endoskeleton encircling the internal organs | Test |
| A complex jawlike mechanism for grinding food | Aristotle's lantern |
| Excretory end of the digestive tract | Anus |
| The bulblike sac inside the endoskeleton that connects to the tube feet and aids in motion and suction | Ampullae |
