Interesting Facts About The Greenland Shark: Second Largest Carnivorous Shark

The Greenland shark (Somniosus microcephalus), also known as the gurry shark, grey shark, sleeper shark, or by the Inuit name Eqalussuaq. It’s the second largest carnivorous shark after the great white, but luckily for us it lives in deep Arctic waters where it rarely encounters people.
The Greenland shark has a sluggish look, with a thickset, cylindrical body and a small head with a short snout and tiny eyes. They’re one of the more unusual sharks out there, in appearance and behavior.
The Greenland Shark is often mistaken for Great White Sharks because of their massive size. They reach up to 24 feet (7.2 meter) in length and weigh up to 3,100 lbs (1,400 kg). The belong to the Somniosidae, or Sleeper Shark family, so they physically resemble Dogfish Sharks. These sharks have very unique habitat, behaviors, and long relationship with humanity.
Here are some interesting facts about the Greenland Shark:
1. Its meat is toxic—at least if you eat it fresh. Its flesh contains high concentrations of trimethylamine oxide (TMAO), which “helps stabilize (the shark’s) enzymes and structural proteins against the debilitating effects of cold and extreme pressure,” according to the ReefQuest Center for Shark Research.
In mammals, though, TMAO gets broken down during digestion and causes a number of horrible symptoms, including “stiff movements, hyper-salivation, vomiting, explosive diarrhea, conjunctivitis, muscular twitching, respiratory distress, convulsions, and—in severe cases—death.”
It also makes people appear as though they’re drunk, which is why, according to the Florida Museum of Natural History, natives of Greenland say that people who are drunk are “shark-sick.”
2. In the deep ocean where the Greenland shark typically lives—it’s been spotted as deep as 7220 feet—it doesn’t need great vision. And that’s a good thing, considering that these sharks are hosts for Ommatokoita elongata, a 2-inch-long parasitic copepod that attaches itself to the shark’s eyes, causing lesions that can lead to blindness.
3. The passive appearance of this deep-water shark is misleading. When hunger strikes, it too can strike with astonishing speed, making a meal of almost anything, including squid, seals, cetaceans, fish, seabirds and dead animals. Studies of its stomach contents have turned up the remains of dogs, horses and even reindeer.
4. In 2006, a Greenland shark fished from the waters of the Saguenay Fjord turned out to be contaminated with industrial waste and heavy metals including mercury. Noting levels of contamination similar to those seen in Saint Lawrence belugas, researchers assumed that the shark had been living in the region for many years.
5. They’re rarely observed and somewhat mysterious. The first underwater photos of a live Greenland shark were taken in the Arctic in 1995, and the first video images of a Greenland shark swimming freely in its natural environment were not obtained until 2003.
6. Eyeball parasites are common. Some populations of Greenland sharks are commonly parasitized by the copepod Ommatokoita elongata. This parasite latches on to the shark’s eye and destroys the corneal tissue, rendering the shark partially blind.
Luckily for the shark, light rarely penetrates the deep waters it prefers and so it relies on other sensory systems to get around and find prey. While over 90% of Arctic Greenland sharks sport this parasite, less than 10% of the Greenland sharks observed in the St. Lawrence are hosts.
7. Their teeth are designed to cut out plugs of flesh. The teeth on the upper jaw are narrow, pointed, and smooth, and anchor the food item as the lower jaw does the cutting. The teeth on the lower jaw are larger and broader and curve sideways. By swinging its head in a circular motion, the shark can cut out a round plug of whatever it’s feeding on.

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