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Like other elasipods, Scotoplanes can be found in very large herds, aggregations of often many thousands of individuals (Gutt and Piepenburg 1991). These aggregations are not believed to be deliberate; rather, the animals tend to gather where food resources are abundant (Dave Pawson, in litt. December 2009). Pawson (1976, 1982) and others have shown that elasipods usually face into the prevailing current, so they can “smell” more palatable sediments and move upstream to better feeding sites. Thus, around carcasses of dead whales on the seafloor, thousands of Scotoplanes can be found, busily gulping down the sediments rich in organic matter derived from the decaying whales (Dave Pawson, in litt. December 2009).
Sea cucumbers are members of a group of marine animals known as echinoderms (“spiny skins”). The 7,000 species of echinoderms that live in today’s oceans also include the starfish, sea urchins, brittle stars, and sea lilies. The 1,500 species of sea cucumbers, or holothurians, can be found in all oceans and at all depths, in a great variety of habitats – some burrow deep into mud or sand, while others may spend their entire lives swimming in midwater. It is in the dark reaches of the deep sea where the sea cucumbers rule. Here, a group known as the elasipods, of which Scotoplanes globosa is an example, can be found in enormous numbers (Dave Pawson, in litt. December 2009).
The bizarre deep-sea sea cucumbers were first described in wonderful detail by Swedish zoologist Hjalmar Théel in 1882, when he wrote a monograph of the astonishing collections amassed by the British research ship HMS Challenger in her round-the-world cruise of 1872-1876. Théel described about 65 new species which he placed in a new Order, the Elasipoda. The so-called elasipods are restricted to deep and cold parts of the world ocean, where they are the dominant large animals in most areas, often comprising more than 95% of the total weight of animals on the deep-sea floor. They are of great importance in the general economy of the deep sea, for as they feed on sediments, and move along on the seafloor, they introduce oxygen into the sediments, thus making them habitable by myriad small animals (Dave Pawson, in litt. December 2009).
Elasipods can vary greatly in shape. Most are more or less cylindrical, but some are quite flat, resembling flatfish in general appearance. They are often very fragile, for their bodies incorporate a large amount of water. As a result, many elasipods may break into gelatinous fragments when they are collected in nets and dredges. Several of these neutrally buoyant elasipods are capable of actively swimming for short to long periods of time. Unique features can include the presence of several very large “walking legs”, which are greatly modified fluid-filled tube feet (tube feet are hydraulically operated locomotory organs possessed by all echinoderms). The upper body surface may carry few to many whip-like so-called papillae, which are also modified tube feet. It is believed that these papillae have a sensory function, helping the animal to “smell” its way to tasty sediments (Dave Pawson, in litt. December 2009).
Additional information and images can be found here: http://blogspotarchive.blogspot.com/2009/07/echinoblog.html.
A typical Scotoplanes has a fat, oval body which may be around 4 inches (10 cm) in length, a mouth surrounded by ten feeding tentacles, five to seven pairs of walking “feet”, and three pairs of papillae on the upper surface of the body. Two of these pairs of papillae are long and whip-like, but the third pair is short and inconspicuous. Usually, the intestine is filled with mud. Photographs and digital images of these animals in situ show that they have a slight resemblance to feeding pigs, hence their common name "sea pig".
Théel (1882) originally described seven species in his genus Scotoplanes. In a recent monograph, Danish biologist Bent Hansen (1975) reduced the number of Scotoplanes species to two. More recent research by Russian biologist Andrey Gebruk (1983) indicated at least five species of Scotoplanes. Recent studies of these animals at the Scripps Institution of Oceanography at La Jolla, California, indicate that there may be as many as eight species (Dave Pawson, in litt. December 2009). Molecular analyses may soon help clarify the systematics (i.e., evolutionary relationships and species boundaries) of this group.
Scotoplanes globosa, commonly known as the sea pig, is a species of sea cucumber that lives in the deep sea.[1] It was first described by Hjalmar Théel, a Swedish scientist. Scotoplanes globosa, along with numerous other sea cucumbers were discovered by Théel during an expedition on HMS Challenger between the years of 1873-1876. Scotoplanes globosa was officially described in 1882, 6 to 9 years after its first sighting. Scotoplanes globosa is most closely related to the genus Peniagone.[2]
Congregations of smaller Scotoplanes globosa are often observed on the ocean floor in groups of 10 to 30.[3] However, groups of Scotoplanes globosa have been observed to be as many as 600 individuals in one congregation. A congregation of Scotoplanes globosa is called a "trawl". These groups of Scotoplanes globosa often appear to all be facing in one direction, into the ocean current. It is believed that this behavior aids S. globosa in the detection of the richest feeding sites. Scotoplanes globosa has also been observed to be the host of multiple deep-sea parasites, such as the small gastropods Stilapex and Crinolamia, and various parasitic crustaceans.[4] These parasites typically bore small holes into the body wall of S. globosa. Scotoplanes globosa are also often accompanied by a symbiotic lithodid crab, the Neolithodes diomedea.[5] It is believed that approximately 22% of Scotoplanes globosa are attended by at least one of these crabs. One possible theory is that these crabs latch onto S. globosa gaining access to nutrients and movement, while the host gets protection from parasites.[5] At this time, scientists are unsure whether the relationship between S. globosa and N. diomedea is mutualistic or commensal.[5]
Scotoplanes globosa is typically 2 to 15 cm in length and appear to be a translucent white color.[6] S. globosa is covered in tube-like feet which are used in locomotion.[6] S. globosa are bilaterally symmetrical, covered in tube-like feet which are used in locomotion and possibly respiration.[7] The tube-like structures found on top of the Scotoplanes globosa are also feet, as opposed to antennae. Scientists are still unsure whether these upper-tube-feet are used in locomotion or used as sensory accessories. They are quite buoyant and are easily displaced by strong currents. Scotoplanes globosa were found to contain only one gonad in both males and females, with evidence that gametogenesis occurred.[7]
Scotoplanes globosa has a soft, round body with five-to-seven pairs of long, tube-like limbs extending from its body.[6] S. globosa uses these limbs for locomotion. They “walk” along the ocean floor using muscle constrictions to push fluid in and out the tube feet cavities.[6] Scotoplanes is the only genus of holothurians that have been observed to "walk" in this manner.
Scotoplanes globosa are found in almost all deep-sea regions in the world. Specifically, S. globosa live on the abyssal plain. They are commonly found off the coast of San Diego, as well as in the Arctic, Atlantic, Pacific, and Indian Oceans.[3] Scotoplanes globosa typically live at depths of over 1,000 m (3,280 ft), and have been found in the deepest locations in the ocean, including the Kermadec Trench at a depth of 6,659 m (21,850 ft) and in the Philippine Trench at a depth of 9,997 m (32,800 ft) by the Galathea expedition in the 1950s.[8] Scotoplanes globosa have been observed to face in a certain direction which is normally against the current and that is because it helps them to search for more fresh and better food quality.[9]
Scotoplanes globosa is a deposit feeder, eating detritus which has sunk to the ocean floor. S. globosa has been observed to strongly prefer consuming fresh, recently fallen (approximately within the last 100 days) sediments on the surface of the ocean floor as opposed to older sediments.[10] These freshly-fallen sediments are more nutrient-rich. Scotoplanes globosa captures food through its mucous-covered tentacles which surround their mouth.[10] S. globosa is also known to congregate around the carcasses of whales which have fallen to the seafloor.[11] Lundsten et al. (2010) determined that S. globosa find deep-sea whale carcasses by smell, as well as other nutrient-rich food sources; the extremely nutrient-rich whale carcasses also attract other deep-sea creatures in large numbers.[11]
Scotoplanes globosa, commonly known as the sea pig, is a species of sea cucumber that lives in the deep sea. It was first described by Hjalmar Théel, a Swedish scientist. Scotoplanes globosa, along with numerous other sea cucumbers were discovered by Théel during an expedition on HMS Challenger between the years of 1873-1876. Scotoplanes globosa was officially described in 1882, 6 to 9 years after its first sighting. Scotoplanes globosa is most closely related to the genus Peniagone.
