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Cuvierian Tubules
Cuvierian tubules are clusters of fine tubes located at the base of the respiratory tree in some sea cucumbers in the genera '' Bohadschia'', ''Holothuria'' and '' Pearsonothuria'', all of which are included in the family Holothuriidae. The tubules can be discharged through the anus when the sea cucumber is stressed. They lengthen when they come into contact with seawater and become adhesive when they encounter objects so that they function as a defence against potential predators. They are named after the French zoologist Georges Cuvier, who first described them. Mode of action There may be several hundred Cuvierian tubules which are attached to the left respiratory tree and lie freely in the coelomic fluid in the body cavity. When stressed, the sea cucumber faces away from the attacker and contracts its body wall muscles sharply. This causes the wall of the cloaca to tear and the anus to gape and the free ends of some of the tubes to be ejected. Water from the respiratory tree i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Cucumber Defence
The sea, connected as the world ocean or simply the ocean, is the body of water, body of saline water, salty water that covers approximately 71% of the Earth's surface. The word sea is also used to denote List of seas, second-order sections of the sea, such as the Mediterranean Sea, as well as certain large, entirely landlocked, saltwater lakes, such as the Caspian Sea. The sea moderates Earth's climate and has important roles in the water cycle, water, carbon cycle, carbon, and nitrogen cycle, nitrogen cycles. Humans harnessing and studying the sea have been recorded since ancient times, and evidenced well into prehistory, while its modern scientific study is called oceanography. The most abundant solid dissolved in seawater is sodium chloride. The water also contains salt (chemistry), salts of magnesium, calcium, potassium, and Mercury (element), mercury, amongst many other elements, some in minute concentrations. Salinity varies widely, being lower near the surface and the mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period. Description Crabs are generally covered with a thick exoskeleton, composed primarily of highly mineralized chitin, and armed with a pair of chelae (claws). Crabs vary in size from the pea crab, a few millimeters wide, to the Japanese spider crab, with a leg span up to . Several other groups of crustaceans with similar appearances – such as king crabs and porcelain crabs – are not true crabs, but have evolved features similar to true crabs through a process known as carcinisation. Environment Crabs are found in all of the world's oceans, as well as in fresh w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bohadschia Vitiensis
''Bohadschia vitiensis'' is a species of sea cucumber in the family Holothuriidae. It is also known as the brown sandfish and brown sea cucumber. It is widespread in shallow waters of the Indo-Pacific. It appears to be able to hybridize with ''Bohadschia argus''. ''Bohadschia vitiensis'' can grow to in total length. The average weight is . It is harvested commercially, which has led to local depletions. References Holothuriidae Fauna of the Indian Ocean Fauna of the Pacific Ocean Animals described in 1868 {{Holothuroidea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holothuria Sanctori
''Holothuria sanctori'' is a species of sea cucumber in the genus ''Holothuria ''Holothuria'' is the type genus of the marine animal family Holothuriidae, part of the class Holothuroidea, commonly known as sea cucumbers. Members of the genus are found in coastal waters in tropical and temperate regions. They are soft bodied ...''. References Holothuriidae Animals described in 1823 {{Holothuroidea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holothuria Pervicax
''Holothuria pervicax'' is a species of sea cucumber in the genus ''Holothuria''. It is commonly called the stubborn sea cucumber due to its inability to be kept alive in captivity. It is commonly found buried beneath rocks on reefs in warm waters. Description ''Holothuria perviax'' is a gray or brown sea cucumber with red-brown papillae and white tube feet for locomotion. Its body is elongated with an oral-aboral orientation and can grow up to 30 centimeters. It has a soft epidermis and a somewhat bumpy body. Its mouth is surrounded by thin branched tentacles with poorly formed spricules found around the body. Distinctions between ''H. perviax'' and sister species fusconierea are hard to find but the main differences are spicule size and slight coloration differences. This species is very high maintenance and requires a specific lifestyle in order to survive. Aquariums have had a very hard time keeping these animals happy and have yet to keep one alive in captivity which has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holothuria Fuscocinerea
''Holothuria fuscocinerea'', the ashy pink sea cucumber, is a species of sea cucumber in the family Holothuriidae. It is placed in the subgenus ''Stauropora'', making its full name ''Holothuria'' (''Stauropora'') ''fuscocinerea''. It is native to shallow water in the tropical and sub-tropical Indo-Pacific. Description This sea cucumber has an oval, cylindrical body, flattened somewhat on the underside, and rounded at both ends. It can reach a length of but is a more normal size. The adult weighs between . The mouth is on the underside at the front and is surrounded by twenty short, brown, branched feeding tentacles. The anus is dark brown or black and has no anal teeth, but is surrounded by five white-tipped papillae. There are Cuvierian tubules in this species. The skin is soft, thick and wrinkled, often with sand adhering to it. It varies in colour, the upperside usually being greyish or brownish, while the underside is a dirty white. There is often a series of dark bars in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holothurin
The holothurins are a group of toxins originally isolated from the sea cucumber '' Actinopyga agassizii''. They are contained within clusters of sticky threads called Cuvierian tubules which are expelled from the sea cucumber as a mode of self-defence. The holothurins belong to the class of compounds known as saponins and are anionic surfactants which can cause red blood cells to rupture. The holothurins can be toxic to humans if ingested in high amounts. Pharmacology Effects on nerves Holothurin is shown to have a blocking effect on nerves in desheathed bullfrog sciatic nerve and rat phrenic nerve preparations, and its potency can be compared to that of cocaine, procaine, and physostigmine. Unlike the other mentioned blocking agents, the disrupting effect of holothurin appears to be quite irreversible upon washing. In another experiment on frog sciatic nerve, holothurin A is shown to be capable of destroying electrical excitability of a node of Ranvier along with basophil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saponin
Saponins (Latin "sapon", soap + "-in", one of), also selectively referred to as triterpene glycosides, are bitter-tasting usually toxic plant-derived organic chemicals that have a foamy quality when agitated in water. They are widely distributed but found particularly in soapwort (genus Saponaria), a flowering plant, the soapbark tree (''Quillaja saponaria'') and soybeans (''Glycine max'' L.). They are used in soaps, medicinals, fire extinguishers, speciously as dietary supplements, for synthesis of steroids, and in carbonated beverages (the head on a mug of root beer). Structurally, they are glycosides, sugars bonded to another organic molecule, usually a steroid or triterpene, a steroid building block. Saponins are both water and fat soluble, which gives them their useful soap properties. Some examples of these chemicals are glycyrrhizin, licorice flavoring; and quillaia (alt. quillaja), a bark extract used in beverages. Uses The saponins are a subclass of terpenoids, the larges ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holothuria Forskali
''Holothuria forskali'', the black sea cucumber or cotton-spinner, is a species of sea cucumber in the family Holothuriidae. It is found at shallow depths in the eastern Atlantic Ocean and the Mediterranean Sea. It was placed in the subgenus ''Panningothuria'' by Rowe in 1969 and is the typetaxon of the subgenus. Sea cucumbers are marine invertebrates and are closely related to the sea urchins and starfish. All these groups tend to be radially symmetric and have a water vascular system that operates by hydrostatic pressure, enabling them to move around by use of many suckers known as tube feet. Sea cucumbers are usually leathery, gherkin-shaped animals with a cluster of short tentacles at one end. Description This sea cucumber has a cylindrical body and can grow to thirty centimetres long. It is usually deep brown or black but sometimes has an underlying yellowish mottling, especially on the underside. The skin is soft yet coarse and tough and is covered with fleshy papillae whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holothuria Leucospilota
''Holothuria leucospilota'', commonly known as the black sea cucumber or black tarzan, is a species of marine invertebrate in the family Holothuriidae. It is placed in the subgenus ''Mertensiothuria'' making its full scientific name ''Holothuria (Mertensiothuria) leucospilota''. It is the type species of the subgenus and is found on the seabed in shallow water in the Indo-Pacific. Description ''Holothuria leucospilota'' is a medium-sized sea cucumber reaching a length of up to when relaxed but it can stretch to about a metre (yard) when extended. It is roughly cylindrical, tapering towards the posterior end. At the anterior end, there are twenty oral tentacles with branched tips. These surround the mouth which is on the under side of the body. The animal is soft and pliable and is covered with fleshy papillae. The usual colour is charcoal grey or reddish-black with pale grey tube feet on the underside but off the African coast it is described as being bright or dark brown with w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autotomy
Autotomy (from the Greek language, Greek ''auto-'', "self-" and ''tome'', "severing", wikt:αὐτοτομία, αὐτοτομία) or self-amputation, is the behaviour whereby an animal sheds or discards one or more of its own appendages, usually as a self-preservation, self-defense mechanism to elude a predation, predator's grasp or to distract the predator and thereby allow escape. Some animals have the ability to regeneration (biology), regenerate the lost body part later. Autotomy has multiple evolutionary origins and is thought to have evolved at least nine times independently in animalia. The term was coined in 1883 by Léon Fredericq, Leon Fredericq. Vertebrates Reptiles and amphibians Some lizards, salamanders and tuatara when caught by the tail will shed part of it in attempting to escape. In many species the detached tail will continue to wriggle, creating a deceptive sense of continued struggle, and distracting the predator's attention from the fleeing prey animal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. Mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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