Large Greenland Shark example essay topic

Sharks live in almost every part of the oceans, from coastal environments to deep-sea habitats. They also live in the warm waters of the tropics to the cold frigid waters of the polar region. The Greenland shark, also known as somniousus Microcephalus, lives in the dark, cold waters of the North Atlantic (I 65). The Greenland shark belongs to the order Squaliforms, more usually known as dogfish sharks. There are 70 species in this order, which includes the spied sharks, spiny dogfish, Sleeper sharks and lantern fish (I 50). Greenland Shark Classification: Kingdom: An amalia Phylum: Cor dates (possessing a notochord) Sub Phylum: Vertebrates (possessing a back bone) Super Class: Gnathostomata (jawed vertebrates) Class: Chondrichthyes (cartilaginous skeleton) Subclass: Elasmobranch as (ribbon like gills) Super Order: Selachii or Selachimopha (shark shaped) Order: Sqauliforms Family: Sqaulidea Species: somniousus Microcephalus (I 185) The sharks habitat largely depends on the water temperature this allows its habitat that ranges from the Polar latitudes to the North Sea in the east and the St. Lawrence River in the West.

The Greenland shark has also wonders south as far as the waters off Cape Hatteras and has also been found in the Gulf of Maine. The shark usually lives in cool water ranging from 2-7 deg Celsius (II 63). However the sharks has also been found in the waters in the Artic Circle. (I 65) Typically the Greenland sharks live at extreme depths. In the winter months the Greenland sharks can be found at the surface and at the edges of ice burgs and glaciers. The sharks will also enter fjords during these months.

However in the warmer months of summer, the sharks dives back to depths and lives at an average depth of 100-400 fathoms and has been caught in water as deep as 600 fathoms (II 63). Depending on season and water temperature, the sharks habitat moves. The diet of a Greenland will eat almost anything that it will come across. With its slow swimming body plan, it includes bottom living shellfish, but it also hunts seals, porpoises and other small whales and sea birds at the surface in its diet (I 65). These sharks also eats many kinds of fish, such as capelin, char, herring, halibut, lumpfish and even salmon.

There has even been fast swimming fish found with its tail bitten off inside the sharks stomach (II 63). A bizarre delicacy for a Greenland shark is reindeer. Some sharks have been found with whole reindeer in their stomachs (IV 55). As you can see the Greenland shark has a wide-ranging diet, however there are no documented attacks on humans, however there are Eskimo legends of these sharks attacking people in kayaks. Many sharks have developed streamline bodies for speed or flat bodies to rest on he bottom. However the Green land sharks does not do either of these, so a rounded flabby body fits them well.

This adaptation is due to the high pressures of the deep. The pressures on the body supports and contains it. The skin does not need to restrain body parts, just holds them in. When a Green land shark is brought to the surface, it is extremely sluggish and flimsy in the low pressure (I 119).

Generally these sharks are very large with 2 spineless dorsal fins equal in size. The upper teeth are long and pointed cusps with smooth edges and the bottom teeth are overlapped and usually larger. The Eskimos who hunt this shark use its extremely sharp teeth for knives and spears. The average size Greenland shark is between 11 ft and 21 ft and weigh about 630 lbs to 2,250 lbs (II 62). The longest Greenland shark recorded is 24 ft and weighed 1 ton (IV 55).

The color of the shark may be brown, black or a purplish gray on its dorsal and ventral sides. On its sides, maybe violet and bands of scattered white and black spots (II 62). For such large shark, Eskimos in the area of the Greenland shark have been fishing and using them for centuries. Some Eskimos are ashamed for fishing for them because they are such a good target. Eskimos in the area say that a single Eskimo can haul up a Greenland shark in a small kayak. They sometimes use a piece of wood for bait and pull it across the surface to entice a shark to attack it (IV 55).

People mainly fish the Greenland shark for its liver oil and flesh used as food and dog food, however they also hunt it because they sometimes enters fjords in the autumn and tear apart the fishnets set up there. A person can get about 30 gallons of oil from one large Greenland shark. Not everyone who fishes for Greenland from a kayak. Instead of wood, mainly salted seal blubber is set on hooks and lowered. Most sharks are caught between 160-220 fathoms. In the winter they can be attacked to the surface with lights.

Once at the surface, the sharks are very sluggish and offer little resistance (II 63). During the early 1900's about 30,000 Greenland sharks were caught every year for their oil ( Vol 5 472). These sharks are still-hunted today for their oil and meat. These sharks are very elusive and are extremely hard to study in the natural environment, in fact not until a few years ago, someone videotaped the first and last video of a Greenland shark in its natural habitat. However it is not hard for scientists to find them during the whaling or hunting season.

Large amounts of these sharks will around whaling or sealing expeditions. Here scientists can get a good look at the sharks. Scientists have gathered information about these sharks through tagging them. Scientists have learned that these sharks grow extremely slow, only about 1 cm a year, some have only grown 8 cm over a 16 year span (II 63). There is no way to know how long these sharks live, the least it is 16 years, the longest one has been tagged. With such a large size, and such a slow growth rate, they hate to be really old to grow that much.

Up this point, these sharks have only been studied for not ever two decades. Many of these sharks have been found with parasitic copepods attached to their eyes. These parasitic do considerable damage to the cornea and impair the sharks vision. Due the depth of water that they live in, it is believed that their vision is not needed at that depth in the dark water (I 77). These parasites might actually help the sharks.

These parasites are biolumiscent and they might attract those fast swimming fish to the oral side of the shark. With out these parasites it is possible that the sharks could not catch as many fish as it does, due to its slow speed. On top of the parasites on its eyes, the Greenland shark also has poisonous flesh. To get rid of the poison n order to eat it, the flesh must be boiled and dried several times (II 63). If the meat is not prepared correctly, it can cause, nausea, vomiting, diarrhea, and abdominal pain, tingling and burning sensation of tongue, throat and esophagus. It can also cause muscular cramps, respiratory distress, coma and death ( Vol 25,905).

This shark may not kill you when its alive, but you have to careful when its dead.

Bibliography

I. Parker II. Castro. Britanica IV. Allen 1. Parker, Steve and Jane. The Encyclopedia fo Sharks. A Firefly Book: Buffalo, 1999.
2. Castro, Jose. THe Sharks of the North American Waters. Texas University Press: US, 1983.
3. Britanica, 15th Edition. Micropedia: Chicago, 1990.
4. Allen, Thomas B. The Shark Almanac. Lioness Press: NY, 1999.