Greenland shark

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Greenland shark
Conservation status: Unknown

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Order:	Squaliformes
Family:	Dalatiidae
Genus:	Somniosus
Species:	S. microcephalus

Binomial name

Somniosus microcephalus
Bloch & Schneider, 1801

The Greenland shark (Somniosus microcephalus), also known as Sleeper shark, Gurry shark, Ground shark or Gray shark, lives in the waters of the North Atlantic Ocean around Greenland and Iceland in depths to 2000 meters.

It might be also referred to as Squalus squatina (non Linnaeus, 1758), Squalus carcharis (Gunnerus, 1776), Somniosus brevipinna (Lesueur, 1818), Squalus borealis (Scoresby, 1820), Squalus norvegianus (Blainville, 1825), Scymnus gunneri (Thienemann, 1828), Scymnus glacialis (Faber, 1829), Scymnus micropterus (Valenciennes, 1832), Leiodon echinatum (Wood, 1846), and Somniosus antarcticus (Whitley, 1939).

Greenland sharks may reach a size of 6 meters and feed mainly on fish and sometimes on mammals like seals. The stomachs of a few Greenland sharks have even been found to contain pieces from reindeer, horses, and even parts of a polar bear.

This shark frequently suffers from a parasitic copepod (Ommatokoita elongata) that attaches itself to the cornea of the eye, feeding on the corneal tissue, and the resulting scar tissue leads to partial blindness of the shark. The copepod is a whitish-yellow creature that is said to be bioluminescent and possibly serves the symbiotic function of attracting prey for the shark, like a fishing lure. This is suggested by the fact that these normally sluggish sharks have been found with much faster-moving animals (e.g., squid) in their stomachs.

The flesh of a Greenland shark is poisonous when fresh. This is due to the presence of the toxin trimethylamine oxide (TMAO), which, upon digestion, breaks down into trimethylamine, producing effects similar to extreme drunkenness. However, it can be eaten if it is boiled in several changes of water or dried or rotted for some months (as by being buried in boreal ground, exposing it to several cycles of freezing and thawing). It is considered a delicacy in Iceland and Greenland. ([1])

Research

Canadian researchers with GEERG (Greenland Shark and Elasmobranch Education and Research Group) have been studying the Greenland shark in the Saguenay Fjord and St. Lawrence Estuary since 2001. The Greenland shark has repeatedly been documented (captured or washed ashore) in the Saguenay since at least 1888. Accidental captures and strandings have also been recorded in the St. Lawrence Estuary for over a century. Current research conducted by GEERG involves the study of the behaviour of the Greenland shark by observing it underwater using scuba and video equipment and by placing acoustic and satellite tags (telemetry) on live specimens.