Greenland shark (Somniosus microcephalus)

The Greenland shark is a large, sluggish shark that is grey or brown in color. The Greenland shark reaches over 20 feet in length and can weigh over a ton, although the Greenland shark is more commonly smaller than this. The Greenland shark has a heavy and cylindrical body and a short, round snout. Interestingly, the Greenland Shark has different shaped teeth. While the teeth in the upper jaw are spear-shaped, the teeth in the Greenland Shark’s lower jaw are short, smooth cusps that bend outward. The teeth in the upper jaw anchor the shark’s bite while the teeth in the lower jaw do most of the cutting.

The Greenland shark is a sub-Arctic shark living farther north than any other known shark species. Native to the waters of the North Atlantic Ocean, the Green shark is more usually found around Canada, Greenland, and Iceland, but has been known to travel down to the waters off the coast of the southern United States.

The Greenland shark feeds on a variety of prey including various marine invertebrates, fish, seabirds, and seals. However, scientists have also found parts of reindeer, dogs, cats and even a polar bears in the stomach of the Greenland shark. Although the Greenland shark is clearly a predator, it is one of the slowest-swimming species of shark and surprisingly its maximum swimming speed is only about half the maximum swimming speed of a healthy seal. There is some evidence suggesting the Greenland shark may ambush seals while they are sleeping. This shark is also known to be attracted by the smell of rotting meat in the water, so the Greenland shark can also be a scavenger.

Baby Greenland sharks are born and the mother shark can carry litters of up to 10 shark pups. The Greenland shark is a slow-growing shark and it appears to be extremely long-lived, possibly more than 100 years, although no specific age range has been determined.

Historically, the Greenland shark had been targeted by shark liver fisheries of several Scandinavian countries during the first half of the 20th century; however commercial fishing for Greenland shark as a source of shark liver oil stopped in the 1960s. Currently, the Greenland shark’s main threat is the Greenland halibut and shrimp trawl fisheries where it is often caught accidentally.

Inuit people used the dried meat of the Greenland shark for both human and sled-dog food, and the shark’s leathery skin to make boots. The meat of the Greenland shark can be toxic if not prepared properly due to the presence of high levels of trimethylamine oxide, which, upon digestion, breaks down into trimethylamine. Trimethylamine oxide is a protein stabilizer often found in sharks, skates and rays, but found in much higher concentrations in deep-water fishes, where it counteracts the protein-destabilizing effects of additional ocean pressure.