Monday, July 29, 2019

The Goblin shark , the retractable jaw, shape and colour of body as Research Paper

The Goblin shark , the retractable jaw, shape and colour of body as well as the electro-sensitive organs for finding prey - Research Paper Example Sharks are mostly found in tropical to warm-temperate waters, and can live in depths as deep as 2000 meters. The most common shape that is associated with sharks is the fusiform shape, such as the one seen in the Great White Shark. However, in reality sharks have various shapes and sizes to suit their prey and environment. The most well-known example of these is the hammerhead shark, from the family Sphyrnidae, which have a flattened structure on their heads that also houses the eyes, making it look like a hammer (Compagno, 1990). There are also other well-known sharks that seem to resemble rays due to their flat bodies, or those that resemble whales with regards to their body and mouth shapes. In this paper, a poorly-known but also one of the most unusual-looking species of sharks, the goblin shark would be discussed as to how its adaptations have lead to its unique body shape, skin color, and jaws. Goblin Shark Descriptions and Physiological Adaptations The goblin shark, (Mitsukuri na owstoni Jordan, 1898) is a deep-dwelling shark that is established as one of the sole extant species of its family, Mitsukurinidae, order Lamniformes, with the rest to be only known from collected fossils (Parsons, Ingram, & Harvard, 2002). It is a poorly- known, elusive deepwater fish, with only around 33 established literatures about its studies, 22 of those are from the vicinity of the Izu Islands, and the rest are scattered across the globe (Duffy, 1997). Thus, until now it is a species that is not well-understood, including its other feeding habits, growth and development patterns, as well as its reproductive cycle. What also makes it harder to study is that once caught off-shore and brought to aquariums, it dies within a span of a week (Compagno, 2000 as cited in Grijalba-Bendeck & Acevedo, 2009; Yano, Miya, Aizawa, & Noichi, 2007). The holotype of the species was captured in 1898 somewhere in the Bay of Tokyo, and most of the other early specimens that were subsequently ca ught were also found near that part of Japan (Jordan, 1898 as cited in Bean, 1905; Dean, 1903; Duffy, 1997; Hussakof, 1909; Parsons, Ingram, & Harvard, 2002). The shark seems to be a well-known species along the coasts of Izu, where the locals call it Tengu-zame, translated as elfin or goblin shark (Bean, 1905). Its large liver is used as an oil source, and the flesh is used as fertilizer. While being seen as rare in most parts of the world, the species seems to be a common bycatch in long line and bottom trawling nets, which suggests that it prefers to live near the meso-pelagic to near-benthic zones (Duffy, 1997; Grijalba-Bendeck & Acevedo, 2009). Other areas where the species are also seen and collected are in Australia, the Indian Ocean, South Africa, French Guiana, Europe, the Gulf of Mexico, and New Zealand (Duffy, 1997; Parsons, Ingram, & Harvard, 2002). The goblin shark has a flat, elongated blade-like snout called the rostrum, small eyes, flabby body, slender teeth and a ca udal fin that has no ventral lobe and resembles that of the thresher shark (Yano, Miya, Aizawa, & Noichi, 2007). This rostral appendage is shorter in adult sharks as compared to younger ones (Bean, 1905; Duffy, 1997; Grija

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