Echinoderms have a few important aspects in common. They have bony ossicles in their body. They have a water-vascular system which pumps water through the madroporite. They also have small jaws that are supported by the water-vascular system. And they have tube feet which they use to attach to objects, for protection, as well as to obtain food. They have radial symmetry and most can regenerate lost limbs.

The following classes are types of echinoderms:

1. Class: Asteroidea–Starfish or Sea Stars (Six-rayed Starfish–Leptasterias hexactis)–sea stars have fairly developed senses of smell, touch, and taste. They also can respond to the presence of light. They normally eat small prey whole, but they have to extrude their stomachs to digest larger prey outside their bodies. Sometimes, sea stars will use their tube feet to help pry open bivalves, and then they will slip their stomachs in between the two shells. 
2. Class: Echinoidea–(*) Sea Urchins–they locomote using short to long, movable spines. Between their spines are small, pincerlike organs called pedicellariae which they use to clean and defend themselves. The pedicellariae also contain a powerful toxin.
3. Class: Ophiuroidea–Brittle Stars (Daisy Brittle Star–Ophiopholis aculeata)
4. Class: Crinoidea–Feather Stars (Florometra serratissima)–feather stars will swim if they are disturbed.
5. Class: Holothuroidea–Sea Cucumbers

Source: Cyhaus

Class Asteroidea

Starfish and Sea Stars

Dissection - Starfish

Model - Starfish

Development & Anatomy Slides

Slide - Starfish Pedicellariae 

Keeps plankton, parasites, and other organisms from settling on their surface.

Slide - Starfish Development

Slide - Starfish Late Gastula

Late gastrulas show greater extension of the gut into the blastocoel than early gastrulas

Slide - Starfish Early & Late Cleavage

Slide - Starfish Bipinnaria Larva

Slide - Starfish Brachiolaria

Larval Stage after occurring after bipinnaria larva

Slide - Young Starfish

Class Ophiuroidea

Brittle stars

Basket Star

Class Echinoidea

Sea Urchins

Dissection - Urchin Aristotle’s lantern 

Urchin’s Heart

Sand Dollars

Class Crinoidea

Fossilized Crinoids

Dried Sea Lilies

Feather Star

Class Holothuroidea

Sea Cucumber

Dissection - Sea Cucumber

Preserved Sea Cucumber