Urchins are echinoderms, spherical in shape and covered with long movable spines. There are about 950 species worldwide. These animals move slowly and feed mostly on algae. They are found on the ocean bottom, usually near rocky shores. In addition to its spines, the sea urchin also has pedicellariae (claw-shaped structure) and tiny tube feet projecting from its body surface. The movable spines are used for locomotion and protection. The pedicellariae are used for defense and for cleaning the body by removing larval animals and small crustaceans.
Sea Cucumber are echinoderms. These marine animals are shaped like soft-bodied cucumbers with leathery skin, typically 10 to 30 cm in length and live on or near the sea floor. There are about 1250 species, most of them are found in the Asia Pacific region. The diet of most cucumbers consists of plankton and/or waste materials, which they gather in with 8 to 30 tube feet that look like tentacles surrounding their mouths. Echinoderms typically possess an internal skeleton composed of plates of calcium carbonate. In most sea cucumbers, however, these have become reduced to microscopic ossicles embedded beneath the skin.
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