Phylum: EchinodermataPhylum: Echinodermata

The Spiny-skinned AnimalsThe Spiny-skinned Animals

Phylum: Echinodermata

Echino – spinyDerm – skinSpiny-Skinned Animals

Sea Lily – Tunicate Cove, Belize

Echinodermata Characteristics

Bilateral as larvae and then Radial as adultsTriploblasticComplete digestive systemRadial nervous system with no brainWater Vascular System (no blood)

Echinoderms have a unique system called the water vascular system. It allows them to move, eat, and exchange gases with their environment.

Ring canal

Radial canal

Ampulla

Tube Feet

Madreporite

Tube feet on sea stars are located on the ventral side of the arms. They can be pulled into slits called ambulacral grooves.

Tube feet on sea stars are located on the ventral side of the arms. They can be pulled into slits called ambulacral grooves. Water is pumped into the tube feet from the ampullae (see previous slide) to cause the tip of the tube foot towiden into a suction cup.

Tube feet on sea stars are located on the ventral side of the arms. They can be pulled into slits called ambulacral grooves. Water is pumped into the tube feet from the ampullae (see previous slide) to cause the tip of the tube foot towiden into a suction cup. By moving each tube foot in tiny steps in a synchronized fashion, echinoderms are able to walk on them. The steps are so small that the animal appears to be gliding.

Four Classes of Echinoderms

Class: Asteroidea – sea stars

Brittle stars have long, stringy arms. They move by walking with their arms. Their tube feet are like cleats to provided added traction.

Four Classes of Echinoderms

Class: Asteroidea – sea starsClass: Echinoidea – sea urchins

South Water Caye, Belize

Four Classes of Echinoderms

Class: Asteroidea – sea starsClass: Echinoidea – sea urchinsClass: Holothuroidea – sea cucumbers

Sea Cucumbers

Four Classes of EchinodermsClass: Asteroidea – sea starsClass: Echinoidea – sea urchinsClass: Holothuroidea – sea cucumbersClass: Crinoidea – crinoids/sea lillies