The Zone Without A Backbone

Phylum:

• Echinoderms are in the phylum Echinodermata.

General Characteristics:

• Echinoderms have an endoskeleton made of many bony plates made from calcium.
• They have radial symmetry.
• Their body parts typically come in multiples of 5.
• Most echinoderms are single sex.
• Echinoderms have a water vascular system. They have fluid filled tubes which cause suction. The tubes are for moving, feeding, and sometimes smelling.

Habitat:

• They live on the bottom of any aquatic environment.

Four Groups of Echinoderms:

• Sea Stars. Sea stars are carnivores and eat mostly bivalves. They eat by turning its stomach inside-out, then the stomach enters the mollusks shell, then chemicals break down food. Sea stars can regenerate if the parts they lost include some of the nerve ring.
• Brittle Stars. Brittle stars have long slender arms with flexible joints. Their tube feet are used for feeding but not moving around.
• Sand Dollars and Sea Urchins. Sand Dollars have flat bodies with short spines to burrow. Sea Urchins have movable spines, five strong teeth to scrape and crush food, usually kelp.
• Sea Cucumbers. Sea Cucumbers can be many colors. Their bodies are soft and flexible, but muscular and strong. Their mouths are surrounded by tentacles. Most sea cucumbers feed by filter feeding. Some will even spit out their internal organs to scare away predators.

Importance of echinoderms:

• They are important predators; they eat a lot of other animals.
• Sea Stars eat bivalves which hurt the economy by eating mollusk farmers' products.
• Many echinoderms eat algae so they control the over-population of algae.

Hooray for Echinoderms!!     

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