ECHINODERMS

Echinoderms are radially symetric, invertibrate marine animals with a water vascular system. They have an endoskeleton, a system of hard plates beneath their skin that helps them maintain their shapes and protects them from predators. Echinoderms rely on their water vascular systems which help them move, eat, and breathe. The water vascular system consists of water-filled partitions in the animal that end in tube feet, which are vital to movement, ingestion, and respiration. Types of Echinoderms include starfish, sea urchins, sea cucumbers, and sea lillies.

Sea Stars/Starfish (Asteroidea)

Asteroidea, or starfish, are the most commonly know echinoderms. They usually have 5 or more arms that are capable of regeneration. Sea stars live at the bottom of the ocean and different species live at any depths. Asteroidea eat by extruding over their prey and excreting digestive enzymes. They move by using the suction-like ends of their tube feet.

Brittle Stars (Ophiuroidea)

Brittle stars are very similar to asteroidea. They have long, flexible arms and a small center. Many brittle stars are nocturnal and eat plankton. They usualy live in areas with strong currents because there is the best flow of plankton. The arms of brittle stars break easily, which allows them to escape from predators, but they regenerate quickly.

Feather Stars (Crinoidea)

Like sea stars and brittle stars, feather stars have many long arms protruding from a central point. They are nocturnal and often curl up their arms during the day. Feather stars use ciri, located on the underside of their bodies, to attatch to coral or rocks. Usually found in areas with strong currents, feather stars feed on plankton.

Sea Urchins (Echinoidea)

Sea urchins are radially symmetric and can be found all over the ocean. They usually live in sandy or rocky areas. Sea urchins normally have spines protruding from their bodies for protection and locomotion. The spines can be poisonous. Sea urchins use tube feet and their spines to move and feed on sponges, small animals, and detritus.

Sea Cucumbers (Holothuroidea)

Although they are bilaterally symmetric, sea cucumbers are classified as echinoderms. Sea cucumbers have long, cylindrical bodes and have appendages similar to tube feet that they use for movement. Small animals, plankton, and waste material are the primary sources of food for sea cucumbers. They live on the ocean floor. When threatened, sea cucumbers can leave some of their vital organs behind and move away or excrete a sticky substance that discourages some predators. The organs lost can be quickly regenerated.

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