Echinoderms
Echinoderms are a group of invertebrates that live in the ocean. In their adult form, their bodies have radial symmetry.
There are four groups of echinoderms:
There are four groups of echinoderms:
- Sea Stars
- Sea Urchins
- Sea Cucumbers
- Sand Dollars
Echinoderms feed off the ocean floor as they move along. Their mouth is located at the center of the body, on the underside. Sea Urchins and sand dollars filter feed and sea stars and sea urchins are active predators.
Echinoderm means "spiny-skinned". Some of the more familiar echinoderms have long sharp spines like the sea urchin.
Echinoderm means "spiny-skinned". Some of the more familiar echinoderms have long sharp spines like the sea urchin.
Echinoderms have a series of hard, stiff plates that act like a skeleton to protect their soft bodies. In sea stars the plates are far apart and allow for the sea star to easily move. The plates in a sand dollar are much closer together which limits mobility.
Echinoderms also have tube feet. Muscles attached to the top of each tube can close the tube off, producing suction at the base of the tube. The tube feet stick to the ocean floor, allowing the echinoderm to pull itself along. The tube feet can also be used for hunting prey. The tube feet pull shells open and the sea star's stomach is pushed out through its mouth and into the bivalve's shell where it begins to digest the bivalve's body.
Label the following items on your sea star.
- anus
- stomach
- tube feet
- central disk
- mouth
- tentacles