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Class: Holothuroidea

Class: Holothuroidea. Sea Cucumbers. General Information. Pickle-shaped animals with feathery tentacles on one end Large range of sizes (some the few centimeters; some species can be over a meter) Large range of habitats – shorelines to the abyssal plains

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Class: Holothuroidea

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  1. Class: Holothuroidea Sea Cucumbers

  2. General Information • Pickle-shaped animals with feathery tentacles on one end • Large range of sizes (some the few centimeters; some species can be over a meter) • Large range of habitats – shorelines to the abyssal plains • Most stay attached to the floor, very few species swim • The muscular walls are eaten in many countries

  3. Feeding & Digestion • Cucumbers have a mouth at one end, a long tube going down the center and an anus at the other end • Mouth • Ringed by tentacles (modified tube feet) • Some species use the tentacles to take in sediment • Some species can extend their tentacles to catch passing food particles • Digestive tube • Contains a stomach and a long, thin, coiled intestine

  4. Skeleton & Muscles • They have no ossicles or large plates to give them a rigid skeleton • How are they classfied as echinoderms? • They have microscopic spicules embedded in their skin • These spicules vary from species to species so they are a useful identification tool • Muscles • Located in the body wall • Developed enough for locomotion • This is the part that is eaten

  5. Respiration • Respiratory Tree • An internal structure that attaches to the intestine • Seawater is “inhaled” through the anal opening and fills the branches of he tree • Body fluid absorb the oxygen and the waste water is “exhaled” back through the anal opening • Sometimes small crabs and fish invade the respiratory tree and set up residence • They don’t hurt the host, but they benefit from the situation • What’s this called? • Commensalism

  6. Protection • Cuverian tubules • Specialized branches of the respiratory tree that resemble long, slender threads • These threads are sticky and sometimes contain toxic chemicals • When ejected, they entangle the offending organism • Evisceration • Some species can forcibly eject their internal organs out of the anal opening • This can happen if they are handled roughly, encounter warm or stagnant water • Under favorable conditions the organs regenerate and the cucumber carries on

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