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59-470: Masikoro Malagasy and Tandroy Malagasy were the chief languages. Sea cucumbers were exported from the province and were an important factor in its economy. The deciduous Andronovory forest was located in the province. The province was the poorest one in Madagascar. In 1993, 8 in every 10 person of the province was living below the poverty line. Despite the production of export crops the province recorded

118-400: A water vascular system that provides hydraulic pressure to the tentacles and tube feet, allowing them to move, and a haemal system . The latter is more complex than that in other echinoderms, and consists of well-developed vessels as well as open sinuses . A central haemal ring surrounds the pharynx next to the ring canal of the water vascular system, and sends off additional vessels along

177-408: A central axis. However, because of their posture, they have secondarily evolved a degree of bilateral symmetry. For example, because one side of the body is typically pressed against the substratum, and the other is not, there is usually some difference between the two surfaces (except for Apodida ). Like sea urchins , most sea cucumbers have five strip-like ambulacral areas running along the length of

236-502: A finer, purer and homogeneous sediment. Therefore, sea cucumbers play a major role in the biological processing of the sea bed (bioturbation, purge, homogenization of the substratum etc.). Most sea cucumbers reproduce by releasing sperm and ova into the ocean water. Depending on conditions, one organism can produce thousands of gametes . Sea cucumbers are typically dioecious , with separate male and female individuals, but some species are protandric . The reproductive system consists of

295-437: A flattened discoid shape, and contains hemoglobin . As a result, in many (though not all) species, both the blood and the coelomic fluid are red in colour. Vanadium has been reported in high concentrations in holothurian blood, however researchers have been unable to reproduce these results. Like all echinoderms, sea cucumbers possess pentaradial symmetry , with their bodies divided into five nearly identical parts around

354-563: A long band of cilia wrapped around its body, and somewhat resembles the bipinnaria larva of starfish. As the larva grows it transforms into the doliolaria , with a barrel-shaped body and three to five separate rings of cilia. The pentacularia is the third larval stage of sea cucumber, where the tentacles appear. The tentacles are usually the first adult features to appear, before the regular tube feet. Numerous small animals can live in symbiosis or commensalism with sea cucumbers, as well as some parasites. Some cleaner shrimps can live on

413-468: A much wider area of the body. Those of the order Apodida have no tube feet or ambulacral areas at all, and burrow through sediment with muscular contractions of their body similar to that of worms, however five radial lines are generally still obvious along their body. Even in those sea cucumbers that lack regular tube feet, those that are immediately around the mouth are always present. These are highly modified into retractile tentacles , much larger than

472-655: A pentamerous radial symmetry. While this can easily be seen in a sea star or brittle star, in the sea cucumber it is less distinct and seen in their five primary tentacles. The pentamerous radial symmetry can also be seen in their five ambulacral canals. The ambulacral canals are used in their water vascular system which is another characteristic that binds this phylum together. The water vascular system develops from their middle coelom or hydrocoel. Echinoderms use this system for many things including movement by pushing water in and out of their podia or "tube feet". Echinoderms tube feet (including sea cucumbers) can be seen aligned along

531-420: A self-defense response. MCTs can be used in many ways but are all similar at the cellular level and in mechanics of function. A common trend in the uses of MCTs is that they are generally used for self-defense mechanisms and in regeneration. Holothurian classification is complex and their paleontological phylogeny relies on a limited number of well-preserved specimens. The modern taxonomy is based first of all on

590-487: A series of narrow tubules branching from a common duct, and lie on either side of the digestive tract. Gas exchange occurs across the thin walls of the tubules, to and from the fluid of the main body cavity. Together with the intestine, the respiratory trees also act as excretory organs, with nitrogenous waste diffusing across the tubule walls in the form of ammonia and phagocytic coelomocytes depositing particulate waste. Like all echinoderms, sea cucumbers possess both

649-456: A single gonad , consisting of a cluster of tubules emptying into a single duct that opens on the upper surface of the animal, close to the tentacles. At least 30 species, including the red-chested sea cucumber ( Pseudocnella insolens ), fertilize their eggs internally and then pick up the fertilized zygote with one of their feeding tentacles. The egg is then inserted into a pouch on the adult's body, where it develops and eventually hatches from

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708-496: A single, branched gonad . They are found on the sea floor worldwide. The number of known holothurian ( / ˌ h ɒ l ə ˈ θj ʊər i ə n , ˌ h oʊ l ə -/ HOL -ə- THURE -ee-ən, HOH -lə- ) species worldwide is about 1,786, with the greatest number being in the Asia–Pacific region. Many of these are gathered for human consumption , and some species are cultivated in aquaculture systems. The harvested product

767-409: A very supple organism. For most echinoderms, their ossicles are found in units making up a three dimensional structure. However, in sea cucumbers the ossicles are found in a two-dimensional network. All echinoderms also possess anatomical feature(s) called mutable collagenous tissues , or MCTs. Such tissues can rapidly change their passive mechanical properties from soft to stiff under the control of

826-514: Is called trivium (with three rows of tube feet), while the dorsal face is named bivium . A remarkable feature of these animals is the "catch" collagen that forms their body wall. This can be loosened and tightened at will, and if the animal wants to squeeze through a small gap, it can essentially liquefy its body and pour into the space. To keep itself safe in these crevices and cracks, the sea cucumber will hook up all its collagen fibers to make its body firm again. The most common way to separate

885-406: Is doubled here by a bilateral symmetry which makes them look like chordates . However, a central symmetry is still visible in some species through five 'radii', which extend from the mouth to the anus (just like for sea urchins), on which the tube feet are attached. There is thus no "oral" or "aboral" face as for sea stars and other echinoderms, but the animal stands on one of its sides, and this face

944-406: Is essentially identical with the coelomic fluid that bathes the organs directly, and also fills the water vascular system. Phagocytic coelomocytes, somewhat similar in function to the white blood cells of vertebrates , are formed within the haemal vessels, and travel throughout the body cavity as well as both circulatory systems. An additional form of coelomocyte, not found in other echinoderms, has

1003-399: Is surgically removed, demonstrating that it does not have a central role in nervous coordination. In addition, five major nerves run from the nerve ring down the length of the body beneath each of the ambulacral areas. Most sea cucumbers have no distinct sensory organs, although there are various nerve endings scattered through the skin, giving the animal a sense of touch and a sensitivity to

1062-696: Is variously referred to as trepang , namako , bêche-de-mer , or balate . Sea cucumbers serve a useful role in the marine ecosystem as they help recycle nutrients, breaking down detritus and other organic matter , after which bacteria can continue the decomposition process. Like all echinoderms , sea cucumbers have an endoskeleton just below the skin, calcified structures that are usually reduced to isolated microscopic ossicles (or sclerietes) joined by connective tissue . In some species these can sometimes be enlarged to flattened plates, forming an armour. In pelagic species such as Pelagothuria natatrix (order Elasipodida , family Pelagothuriidae ),

1121-513: The American Cancer Society , although it has been used in traditional Asian folk medicine for a variety of ailments, "there is little reliable scientific evidence to support claims that sea cucumber is effective in treating cancer, arthritis, and other diseases" but research is examining "whether some compounds made by sea cucumbers may be helpful against cancer". Calcareous Too Many Requests If you report this error to

1180-500: The Florida reefs, has a volume of well over 500 cubic centimeters (31 cu in), and 25–30 cm (10–12 in) long. Most possess five rows of tube feet (called " podia "), but Apodida lacks these and moves by crawling; the podia can be of smooth aspect or provided with fleshy appendages (like Thelenota ananas ). The podia on the dorsal surface generally have no locomotive role, and are transformed into papillae. At one of

1239-636: The Indigenous Australians of Arnhem Land from at least the 18th century and probably earlier. This is the first recorded example of trade between the inhabitants of the Australian continent and their Asian neighbours . There are many commercially important species of sea cucumber that are harvested and dried for export for use in Chinese cuisine as hoisam . Some of the more commonly found species in markets include: According to

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1298-400: The intestine . The intestine is typically long and coiled, and loops through the body three times before terminating in a cloacal chamber, or directly as the anus . Sea cucumbers have no true brain . A ring of neural tissue surrounds the oral cavity, and sends nerves to the tentacles and the pharynx . The animal is, however, quite capable of functioning and moving about if the nerve ring

1357-482: The South Pacific sea cucumbers may be found in densities of 40 individuals/m (3.7 individuals/sq ft). These populations can process 19 kilograms per square metre (3.9 lb/sq ft) of sediment per year. The shape of the tentacles is generally adapted to the diet, and to the size of the particles to be ingested: the filter-feeding species mostly have complex arborescent tentacles, intended to maximize

1416-434: The abyssal genus Scotoplanes . 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. A few genera, such as Sphaerothuria , retain relatively large plates, giving them a scaly armour. Sea cucumbers can be found in great numbers on the deep seafloor, where they often make up

1475-443: The animal to elongate and the introvert to extend. Anterior to the ossicles lie further muscles, contraction of which cause the introvert to retract. The body wall consists of an epidermis and a dermis and contains smaller calcareous ossicles, the types of which are characteristics which help to identify different species. Inside the body wall is the coelom which is divided by three longitudinal mesenteries which surround and support

1534-432: The animals able to control their own buoyancy, making it possible for them to either live on the ocean floor or to actively swim or float over it in order to move to new locations, in a manner similar to how the group Torquaratoridae floats through water. Holothurians appear to be the echinoderms best adapted to extreme depths, and are still very diversified beyond 5,000 metres (16,000 ft) deep: several species from

1593-555: The anus from the water), and to develop into their adult stage of life. Many polychaete worms (family Polynoidae ) and crabs (like Lissocarcinus orbicularis ) have also specialized to use the mouth or the cloacal respiratory trees for protection by living inside the sea cucumber. Nevertheless, holothurians species of the genus Actinopyga have anal teeth that prevent visitors from penetrating their anus. Sea cucumbers can also shelter bivalvia as endocommensals, such as Entovalva sp . Sea cucumbers are often ignored by most of

1652-416: The anus, corresponds to the aboral pole. Thus, compared with other echinoderms, sea cucumbers can be said to be lying on their side. The body of a holothurian is roughly cylindrical. It is radially symmetrical along its longitudinal axis, and has weak bilateral symmetry transversely with a dorsal and a ventral surface. As in other Echinozoans , there are five ambulacra separated by five ambulacral grooves,

1711-427: The body from the mouth to the anus. The three on the lower surface have numerous tube feet , often with suckers, that allow the animal to crawl along; they are called trivium . The two on the upper surface have under-developed or vestigial tube feet, and some species lack tube feet altogether; this face is called bivium . In some species, the ambulacral areas can no longer be distinguished, with tube feet spread over

1770-466: The classic sausage-shape, while others resemble caterpillars. The mouth is surrounded by tentacles, which can be pulled back inside the animal. Holothurians measure generally between 10 and 30 centimetres (3.9 and 11.8 in) long, with extremes of some millimetres for Rhabdomolgus ruber and up to more than 3 metres (9.8 ft) for Synapta maculata . The largest American species, Holothuria floridana , which abounds just below low-water mark on

1829-430: The extremities opens a rounded mouth, generally surrounded with a crown of tentacles which can be very complex in some species (they are in fact modified podia); the anus is postero-dorsal. Holothurians do not look like other echinoderms at first glance, because of their tubular body, without visible skeleton nor hard appendixes. Furthermore, the fivefold symmetry, classical for echinoderms, although preserved structurally,

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1888-426: The family Elpidiidae ("sea pigs") can be found deeper than 9,500 metres (31,200 ft), and the record seems to be some species of the genus Myriotrochus (in particular Myriotrochus bruuni ), identified down to 10,687 metres (35,062 ft) deep. In more shallow waters, sea cucumbers can form dense populations. The strawberry sea cucumber ( Squamocnus brevidentis ) of New Zealand lives on rocky walls around

1947-412: The first-level administrative divisions when the provinces were abolished in 2009. They are sub-divided into 21 districts: Sea cucumber Sea cucumbers are echinoderms from the class Holothuroidea ( / ˌ h ɒ l ə ˌ θj ʊəˈr ɔɪ d i ə , ˌ h oʊ l ə -/ HOL -ə-thyuu- ROY -dee-ə, HOH -lə- ). They are marine animals with a leathery skin and an elongated body containing

2006-518: The highest rural poverty . The average fertility rate per woman was above 5. With 77 percent of its population being illiterate, Tolaira was the most illiterate province of Madagascar. Only 22 percent of the province's population had received primary level education. The commercially valuable softwood tree Givotia madagascariensis , found in Antananarivo and Toliara provinces was endemic to Madagascar. The oil producing plant moringa drouhardii

2065-402: The interambulacra. The ambulacral grooves bear four rows of tube feet but these are diminished in size or absent in some holothurians, especially on the dorsal surface. The two dorsal ambulacra make up the bivium while the three ventral ones are known as the trivium. At the anterior end, the mouth is surrounded by a ring of tentacles which are usually retractable into the mouth. These are called

2124-430: The internal organs. A pharynx lies behind the mouth and is surrounded by a ring of ten calcareous plates. In most sea cucumbers, this is the only substantial part of the skeleton, and it forms the point of attachment for muscles that can retract the tentacles into the body for safety as for the main muscles of the body wall. Many species possess an oesophagus and stomach , but in some the pharynx opens directly into

2183-405: The locomotive tube feet. Depending on the species, sea cucumbers have between ten and thirty such tentacles and these can have a wide variety of shapes depending on the diet of the animal and other conditions. Many sea cucumbers have papillae, conical fleshy projections of the body wall with sensory tube feet at their apices. These can even evolve into long antennae-like structures, especially on

2242-448: The majority of the animal biomass. At depths deeper than 8,900 m (5.5 mi), sea cucumbers comprise 90% of the total mass of the macrofauna. Sea cucumbers form large herds that move across the bathygraphic features of the ocean, hunting food. The body of some deep water holothurians, such as Enypniastes eximia , Peniagone leander and Paelopatides confundens , is made of a tough gelatinous tissue with unique properties that makes

2301-687: The marine predators because of the toxins they contain (in particular holothurin ) and because of their often spectacular defensive systems. However, they remain a prey for some highly specialized predators which are not affected by their toxins, such as the big mollusks Tonna galea and Tonna perdix , which paralyzes them using powerful poison before swallowing them completely. Some other less specialized and opportunist predators can also prey on sea cucumbers sometimes when they cannot find any better food, such as certain species of fish ( triggerfish , pufferfish ) and crustaceans (crabs, lobsters, hermit crabs ). Some species of coral-reef sea cucumbers within

2360-477: The nervous system and coordinated with muscle activity. Different echinoderm classes use MCTs in different ways. The asteroids, sea stars, can detach limbs for self-defense and then regenerate them. The Crinoidea, sea fans, can go from stiff to limp depending on the current for optimal filter feeding. The Echinoidea, sand dollars, use MCTs to grow and replace their rows of teeth when they need new ones. The Holothuroidea, sea cucumbers, use MCTs to eviscerate their gut as

2419-450: The ocean floor. Most of them have specific swimming appendages, such as some kind of umbrella (like Enypniastes ), or a long lobe on top of the body ( Psychropotes ). Only one species is known as a true completely pelagic species, that never comes close to the bottom: Pelagothuria natatrix . Holothuroidea are generally scavengers , feeding on debris in the benthic zone of the ocean. Exceptions include some pelagic cucumbers and

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2478-425: The order Aspidochirotida can defend themselves by expelling their sticky cuvierian tubules (enlargements of the respiratory tree that float freely in the coelom ) to entangle potential predators. When startled, these cucumbers may expel some of them through a tear in the wall of the cloaca in an autotomic process known as evisceration . Replacement tubules grow back in one and a half to five weeks, depending on

2537-500: The phylum Echinodermata. This is one of the most distinctive and diverse phyla, ranging from starfish to urchins to sea cucumbers and many other organisms. The echinoderms are mainly distinguished from other phyla by their body plan and organization. The earliest sea cucumbers are known from the middle Ordovician , over 450 million years ago. The apodida is the sister group to the other orders of sea cucumbers. All echinoderms share three main characteristics. When mature, echinoderms have

2596-451: The pouch as a juvenile sea cucumber. A few species are known to brood their young inside the body cavity, giving birth through a small rupture in the body wall close to the anus. In all other species, the egg develops into a free-swimming larva , typically after around three days of development. The first stage of larval development is known as an auricularia , and is only around 1 mm (39 mils ) in length. This larva swims by means of

2655-491: The presence of light. There are, however, a few exceptions: members of the Apodida order are known to possess statocysts , while some species possess small eye-spots near the bases of their tentacles. Sea cucumbers extract oxygen from water in a pair of "respiratory trees" that branch in the cloaca just inside the anus , so that they "breathe" by drawing water in through the anus and then expelling it. The trees consist of

2714-463: The presence or the shape of certain soft parts (podia, lungs, tentacles, peripharingal crown) to determine the main orders, and secondarily on the microscopic examination of ossicles to determine the genus and the species. Contemporary genetic methods have been helpful in clarifying their classification. Taxonomic classification according to World Register of Marine Species : To supply the markets of Southern China , Makassar trepangers traded with

2773-448: The primary tentacles and were present in the common ancestor of echinoderms, but have been lost in all the other classes of the phylum, and may be simple, branched or arborescent. They are known as the introvert and posterior to them there is an internal ring of large calcareous ossicles. Attached to this are five bands of muscle running internally longitudinally along the ambulacra. There are also circular muscles, contraction of which cause

2832-400: The radial canals beneath the ambulacral areas. In the larger species, additional vessels run above and below the intestine and are connected by over a hundred small muscular ampullae, acting as miniature hearts to pump blood around the haemal system. Additional vessels surround the respiratory trees, although they contact them only indirectly, via the coelomic fluid . Indeed, the blood itself

2891-403: The side of their axes. While echinoderms are invertebrates, meaning they do not have a spine, they do all have an endoskeleton that is secreted by the mesenchyme . This endoskeleton is composed of plates called ossicles. They are always internal but may only be covered by a thin epidermal layer like in sea urchin's spines. In the sea cucumber the ossicles are only found in the dermis, making them

2950-412: The skeleton is absent and there is no calcareous ring. Sea cucumbers are named for their resemblance to the fruit of the cucumber plant. Most sea cucumbers have a soft and cylindrical body, rounded off and occasionally fat in the extremities, and generally without solid appendages. Their shape ranges from almost spherical for "sea apples" (genus Pseudocolochirus ) to serpent-like for Apodida or

3009-423: The smallest known species are just 3 mm (0.12 in) long, and the largest can reach 3 meters (10 ft). The body ranges from almost spherical to worm-like, and lacks the arms found in many other echinoderms, such as starfish . The anterior end of the animal, containing the mouth, corresponds to the oral pole of other echinoderms (which, in most cases, is the underside), while the posterior end, containing

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3068-590: The southern coast of the South Island where populations sometimes reach densities of 1,000 animals/m (93 animals/sq ft). For this reason, one such area in Fiordland is called the strawberry fields. Some abyssal species in the abyssal order Elasipodida have evolved to a "benthopelagic" behaviour: their body is nearly the same density as the water around them, so they can make long jumps (up to 1,000 metres or 3,300 feet high), before falling slowly back to

3127-545: The species Rynkatorpa pawsoni , which has a commensal relationship with deep-sea anglerfish . The diet of most cucumbers consists of plankton and decaying organic matter found in the sea. Some sea cucumbers position themselves in currents and catch food that flows by with their open tentacles. They also sift through the bottom sediments using their tentacles. Other species can dig into bottom silt or sand until they are completely buried. They then extrude their feeding tentacles, ready to withdraw at any hint of danger. In

3186-675: The species. The release of these tubules can also be accompanied by the discharge of a toxic chemical known as holothurin , which has similar properties to soap. This chemical can kill animals in the vicinity and is one more method by which these sedentary animals can defend themselves. If the water temperature becomes too high, some species of sea cucumber from temperate seas can aestivate . While they are in this state of dormancy they stop feeding, their gut atrophies, their metabolism slows down and they lose weight. The body returns to its normal state when conditions improve. Holothuroidea (sea cucumbers) are one of five extant classes that make up

3245-522: The subclasses is by looking at their oral tentacles. Order Apodida have a slender and elongate body lacking tube feet, with up to 25 simple or pinnate oral tentacles. Aspidochirotida are the most common sea cucumbers encountered, with a strong body and 10–30 leaflike or shield-like oral tentacles. Dendrochirotida are filter-feeders, with plump bodies and 8–30 branched oral tentacles (which can be extremely long and complex). Sea cucumbers are typically 10 to 30 cm (4 to 12 in) in length, although

3304-428: The surface area available for filtering, while the species feeding on the substratum will more often need digitate tentacles to sort out the nutritional material; the detritivore species living on fine sand or mud more often need shorter "peltate" tentacles, shaped like shovels. A single specimen can swallow more than 45 kilograms (99 lb) of sediment a year, and their excellent digestive capacities allow them to reject

3363-451: The tegument of holothurians, in particular several species of the genus Periclimenes (genus which is specialized in echinoderms), in particular Periclimenes imperator . A variety of fish, most commonly pearl fish , have evolved a commensalistic symbiotic relationship with sea cucumbers in which the pearl fish will live in sea cucumber's cloaca using it for protection from predation, a source of food (the nutrients passing in and out of

3422-412: Was endemic to Toliara province. Deforestation was a major issue for the province. In April 1971, a peasant rebellion was organised by MONIMA leader Monja Joana. The peasants refused to pay taxes and the government retaliated by dissolving MONIMA and deporting Joana. Toliara province offered poor transport and security facilities. Potable water was accessible to only 24.9% of the province's households. It

3481-502: Was rich in terms of minerals. Toliara province was in the news in July 2005 for its mining activity. The provinces were abolished following the results of Malagasy constitutional referendum, 2007 which led to the formation of 22 smaller areas ( faritra or regions) to facilitate regional development. Toliara Province was divided into four regions of Madagascar - Androy , Anosy , Atsimo Andrefana and Menabe . These four regions became

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