"Sleepy with small head".. this is the meaning of the scientific name Somniosus microcephalus, but in reality Greenland shark is not only a slow abysmal creature. Also for this animal in fact, in spite of uis name, powerful and fast releases to capture the preys and resistance and tenacity in hunting are possible..

Greenland shark is one of the few sharks, if not the only, that swims in the icy waters of the north Atlantic and in the arctic regions. This shark can reach the coasts of France and Portugal and some sightings consider him also present in the south Atlantic, next to Argentina and in the Antarctic regions. Because of the difficulties of observation in nature (deep arctic waters with temperatures near to the zero and with almost nonexistent visibility) there are still few information on the biology and on the behavior of this great shark.

The Greenland shark in fact eaches notable dimensions, from the 240-400 cm to a maximum of 640 cm (is held possible the maximum dimension of 730 cm). 

A real giant of the polar regions, of grey-brown color, uniform, with some times clearer stains on the back. An exceptional evolutionary adaptation allows this sea creature to quietly live in waters with temperatures that go since 0.6 to the 12 centigrade degrees and to sink him up to 1200 m of depth (during the winter months more next to the surface, in the summer among 180-550 m). 

The face of Greenland sharl is short and rounded off and the eyes are small. The two dorsal fins are without thorns, the anal fin is absent. Also the pectoral fins and ventral ones are of small dimensions while the caudal fin is enough developed, both the superior lobe and that inferior.
The gills are decidedly small and this characteristic suggests that the Greenland shark, also endowed with power and possibility of brief fast releases to chase, for the most greater part of the time swims in slow and constant way, with a least energetic consumption.

The teeth are different in the two arcades, in that superior they are thin and pointed, while in that inferior more breadths, resistant, with the cusp moved toward the outside.

The Greenland shark nourishes him both of carcasses of sea mammals and of real preys, to pursue and to capture, as bony fishes, and seals.
The sight doesn't seem to be very developed, the eyes in fact are small and in the middle depths in which this shark swims the brightness is almost absent..
Besides these elements, in a great percentage of Greenland sharks, one of the two eyes are attached by a specific parasite, the Ommatokoita elongata. The adult female of this parasite, long around 5 cm, anchors him in the cornea of the eye of the shark, bringing to an almost total blindness for that visual field. Greenland sharks are rare in which both the eyes are attacked from Ommatokoita elongata.
Despite this important trouble to the sight the animal doesn't seem to have particolar problems, using other efficient senses. 

It would result even that the parasitic Ommatokoita elongata can be able to send a small light that could attract the preys near in the mouth of the Greenland shark, preys attracted by a small luminescence in the dark and icy depths of the arctic waters.
(currently any scientific test can confirm this theory) 

The reproduction of this shark seems to be viviparous without placenta. 

The native people of Greenland have fished for a long time this shark to use the oil of the great liver, rich of vitamin Á. and also for the meat, that results edible if dried, toxic, even poisonous, if eaten fresh.
The skin was often used for manufacturing boots, evidently very resistant and the teeth, those of the inferior arcade into efficient razors.
The Greenland shark is not considered dangerous for the man, above all because a meeting would be rare with this abysmal creature in the arctic waters, but its great dimensions would push however to extreme caution in a possible directed contact..

Greenland shark video at great depth

Bibliography: "Sharks & Rays, Elasmobranch Guide Of The World". Ralf M. Hennemann,
"Sharks of the world", Leonard Compagno, M. Dando, S. Fowler,

Marco Angelozzi - www.prionace.it

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