Explore the Collection: Echinoderms
Feather stars, sea stars, brittle stars, sea urchins and sea cucumbers belong to the phylum Echinodermata, which means ‘spiny skinned’. Animals of this group have an internal skeleton, which consists of plates or microscopic spicules that often bear spines.
Although animals that belong to this group may appear to be very different in appearance, they actually have similarities in their structure. All adults possess radial symmetry, which refers to their bodies being arranged around a central mouth. The bodies of these animals are usually divided into five sections.
Did you know?
All echinoderms possess a large number of tiny tube feet, called podia. The movement of these tube feet is achieved by the animals forcing water into them through a network of canals, known as a water vascular system.
Echinoderm Classes:
Click on any of the Echinoderm classes below to read more.
Feather Stars
Feather stars possess upward branching arms, giving them a cup-like appearance. The arms, similar to feathers in appearance, branch from a central disc and can range in number from five up to 200.
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Sea Stars
Sea stars generally take the shape of either a star or a pentagon, and typically have five arms. The upper body consists of a network of plates embedded in the flesh.
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Brittle Stars
Brittle stars differ from sea stars as they possess a distinct central disc, from which their arms extend. The tube feet on the arms of brittle stars are reduced and are generally used during feeding, but not for movement.
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Sea Urchins
Sea urchins possess many hard plates beneath their skin that form a hard protective shell, known as a test. This test remains intact once the animal dies and can often be found washed up on beaches.
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Sea Cucumbers
Sea cucumbers can generally be found living on the ocean floor, in crevices of rocks and corals, or burrowed in soft sand and mud. While most sea cucumbers possess five bands of tube feet, those that run along the lower surface are used for locomotion.
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