Sea cucumber

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  • 1. CLASS HOLOTHUROIDEA (SEA CUCUMBERS) By: Christian Jay Rayon Nob BS-Marine Biology Mindanao Sate University-Naawan Campus

2. Sea cucumbers are an abundant and diverse group of worm-like and usually soft-bodied echinoderms. Bony fragments along the animal's skin give the appearance of bumps and warts similar to the vegetable from which the sea cucumber derives its name. They are distinguished from other echinoderms in having the polar axis greatly lengthened, which results in the body having an elongated cucumber shape. 3. HISTORY ON SYSTEMATICS 4. The name Holothuroidea is derived from the term holothourion named by Aristotle. He based many of his accounts of plants and animals, including marine forms, on first-hand observations. He refers this organism from the sponges, which is without feeling and motionless, as well as being free and unattached and separated from the ground but plant-like. This is an unexpectedly inaccurate description of holothuroids from the father of western observation. 5. The term holothurion was also applied to cnidarians, tunicates and priapulid worms until the late 18th century. Belon (1553) was the first to recognize the resemblance of holothuroids to other echinoderms by the similarity of their tube feet in 19th century. Holothuroids, because of their soft body and bilateral, vermiform appearance, often served as a connection in the linearly arranged classificatory arrangements between echinoderms . 6. Alexander Agassiz in an 1865 letter to Fritz Muller wrote that Darwinists would undoubtedly interpret the similarities of echinoderm. Holothuroids, because of their soft body and bilateral, vermiform appearance, often served as a connection in the linearly arranged classificatory arrangements between echinoderms. Holothuroids were often seen as the most advanced echinoderm because they were the least radially symmetrical . 7. Carolus Linnaeus which originally referred most holothuroids to Fistularia, a name preoccupied by a fish. Holothuria was formally assigned to the class of echinoderms in 1924. Bohadsch (1761) and Pallas (1766) provide the first anatomical accounts of holothuroids. Cucumaris marimus is the first discovered species of sea cucumber. 8. As for most soft-bodied animals, holothuroids have a poor fossil record. Published accounts exist of body fossils for about 19 species. Most ancient holothuroids are known from fossils of isolated ossicles. Entire or isolated elements of the calcareous ring are also known. 9. Holothuroids probably evolved by at least the Lower Silurian, most likely from a little known group of extinct Palaeozoic echinoderms called ophiocistioids. The oldest reported body fossil of a holothuroid is from the Lower Devonian, while the oldest undoubted ossicle is from the Upper Silurian. 10. BIODIVERSITY OF SEA CUCUMBER 11. More than 1500 species of sea cucumber have been described worldwide, with the highest number in the Asia Pacific. Over 170 sea cucumber species are recorded in the Philippines, majority of them can be found in Mactan, Cebu. Stichopus is the largest species that is found in the Philippines that may attain a length greater than 3 ft. and a diameter of 8 in. Sea cucumbers are not only important on aquatic organisms but also on economically valued. 12. They are often dried to preserve them and are used as food and in herbal and pharmaceutical medicines. Sea cucumbers contain several vitamins such as: Mucopolysaccharides chondroitins protein vitamins A & C riboflavin niacin Calcium iron magnesium zinc sodium carbohydrates 13. Living holothuroids are divided into six orders. Each order is described according to its taxonomic diversity and major diagnostic features: Apodida Footless sea cucumbers, contains about 269 species in 32 genera and three families. Tentacles are digitate, pinnate or, in some small species, simple. Respiratory trees are absent. Tube feet are completely absent. 14. Elasipodida Deep-sea sea cucumbers, contains about 141 species in 24 genera and five families. Tentacles are shield-shaped and used in shoveling sediment. Aspidochirotida Shield-tentacle sea cucumbers, there are about 340 species in 35 genera and three families. Tentacles are shield-shaped. Respiratory trees are present. Molpadiida Rat-tailed sea cucumbers, there are about 95 species in 11 genera and four families. Tentacles are simple. Respiratory trees are present. 15. Dendrochirotida Contains about 550 species in 90 genera and seven families. Tentacles are highly branched and extended to filter material from the water column. Respiratory trees are present. Dactylochirotida Contains about 35 species in seven genera and three families. Tentacles are simple or with a few small digits. Respiratory trees are present. 16. Parastichopus californicus California Sea Cucumber The California Sea Cucumber grows up to 50cm long. They range in colors from red in juveniles to brown or mottled brown, with all white individuals occurring rarely. They are covered on the dorsal side with flesh colored papillae and on the ventral side by tube feet. A circle of peltate feeding tentacles surround a sub terminal mouth, directed ventrally at the anterior end. 17. Cucumaria miniata Burrowing Sea Cucumber The Orange sea cucumber received its Latin name, Cucumaria because it resembles a cucumber. Although it seems to be completely soft and fragile, it actually has bone-like plates in the body wall called ossicles. To stay attached to the holes between the rocks, the cucumber uses tube feet that you can see in the image above in 5 rows around the circumference of the body. 18. Eupentacta quinquesemita White Sea Cucumber Eupentacta quinquesemita is stiff to touch due to abundant calcareous ossicles in the skin and tube feet. The body grows 4-8 cm in length. The non-retractile tube feet give it a spiny look. The two ventral feeding tentacles are smaller than the other eight. This character is useful for identifying this species when only the tentacles are visible. The expanded tentacles are creamy white with tinges of yellow or pink at the bases. 19. Holothuria scabra Sandfish The sandfish is grayish-black on the upper side with dark-colored wrinkles but paler on the underside. It grows up to 4cm long, is broader than it is high and has a pliable skin. It is covered by calcareous spicules in the form of tablets and button. This species is found in shallow water on soft sediments throughout the Indo-Pacific region that range into the depth of low tide to 30 meters. 20. Stichopus vastus Brown curryfish They are found in Indo-Pacific Ocean. Inhabits sandy and rocky inner and outer reef bottom areas near heavy growths of coral. Can reach a length of about 26 inches (70 cm). Feeds on detritus and organic matter that is sifted from the substrate. Rarely found in the trade and too large for most aquaria. 21. Thelenota ananas Prickly redfish They can grey, orange, to red sea cucumber, often with a purple cast. It is a very large species (to 600 (750) cm), square in cross section with prominent 'cockscomb' papillae over its upper surface. It has a thick but pliable body and a smooth tegument. Depth range is 135 m. 22. Thelenota anax Amberfish T. anax is a cream or brown sea cucumber mottled with red or brown. Inhabits sandy and rocky inner and outer reef bottom areas. And can reach a length of about 40 inches (100 cm). Feeds on detritus and organic matter that is sifted from the substrate. 23. Holothuria whitmaei Blackteatfish Holothuria whitmaei is a large, solid holothurian that is always black in color and often has a thin coating of sand clinging to the upper surface. There are often several protrusions around the edge of the body where the flat underside meets the steeply-rising sides, giving the species its common name of Black Teatfish. 24. Holothuria atra Lollyfish Holothuria atra is a sausage-shaped sea cucumber that can grow to a length of 60 centimetres (24 in) but 20 centimetres (7.9 in) is more common size. It has a smooth, pliable, entirely black skin which often has sand adhering to it, especially in smaller individuals. The mouth is on the underside at one end and is surrounded by a fringe of 20, black, branched tentacles. The anus is at the other end. 25. Stichopus horrens Dragonfish (Selenkas sea cucumber) Stichopus horrens is a variable, grey to green or black sea cucumber. It is often variegated with dark patches. It is a medium- sized species (to 300 mm) with a smooth tegument but large and irregular papillae. The big tubercles and irregular body form give an "irregular, soft and almost repulsive" appearance. S. horrens may be found on reefs, below rocks on flats. 26. a. anal teeth: usually five in number; each a hard (calcified) triangular structure embedded in the anal wall. b. anus: posterior (rear) opening of the gut. c. cuverian organs: consisting of sticky white thread- or ribbon-like structures which are thrown out from the anus of some species; a special defene mechanism. d. eviscerate: to throw out its guts (through the anus). e. papillae: similar to tube feet but smaller (commonly a few millimeters up to more than a centimeter in length), they are conical and pointed. Occurring chiefly on the back, they are also often seen on processes of the body wall. 27. f. pedicels adapted from tube feet, they are small and tubular, as distinct from the conical papillae. Occurring on the back, they are commonly only a few millimeters long. g. Podia Tube-like feet, generally ending in flat disks, which enable the sea cucumber to adhere to the substrate when moving. h. water vascular system It provides hydraulic pressure to the tentacles and tube feet allowing them to move. i. Tentacles Tentacles around the mouth are used to gather food. j. Bivium the dorsal part of the body in the pentaradial symmetry, w