Are There Any Arctic Sharks?
In response to a question about whether there are any Arctic Sharks, I responded:
While shark diversity and abundance are generally greatest in warmer waters, a few species regularly inhabit cold waters within the Arctic Circle. Of some 465 known shark species, I know of only eight that have been recorded from the Arctic. These are: the Blue Shark (Prionace glauca), Porbeagle (Lamna nasus) and Salmon Shark (Lamna ditropis), Basking Shark (Cetorhinus maximus), Bluntnose Sixgill (Hexanchus griseus), Spiny Dogfish (Squalus acanthias), Pacific Sleeper (Somniosus pacificus) and the Greenland Shark (Somniosus microcephalus).
Greenland Shark (Somniosus microcephalus)
Of these cold-water creatures, the Greenland Shark is one of the most fascinating. Growing to a length of at least 6.4 metres, the Greenland Shark rivals the Great White (Carcharodon carcharias) in dimension if not reputation. Greenland Sharks are preternaturally sluggish. In fact, Inuit in Canada's far north have been known to catch these giant sharks with their bare hands, hauling them onto the ice like so much wet laundry. Yet, in addition to scavenging Beluga and Narwhal carcasses, Greenland Sharks are also known to feed on such speedy prey as salmon and Arctic seals.
How Greenland Sharks manage to catch these quicksilver entrees is something of a mystery. Most Greenland Sharks have an elongate, pinkish-white parasite attached to each cornea. These parasites are a type of copepod crustacean and until recently were believed to be bioluminescent. It was therefore suggested that these glowing eye parasites could help lure curious prey to their sluggish hosts, which could then ambush the prey from close range. But the lack of biolumenescence in these parasites puts the bite on this otherwise nifty theory.
However, a number of intriguing reports from Canadian wildlife biologists suggest that the Greenland Shark may not be as sluggish as it is reputed to be. The Greenland Shark has a short, broad tail that is ideally suited for rapid, burst accelerations. Reports from Nunavit and Baffin Island indicate that Caribou drinking from the cold, clear water of rivermouths are sometimes attacked by Greenland Sharks, grabbed by the face and neck, much like an African wildebeest at a watering hole might be ambushed by a submerged crocodile.
So, YES, there are a few Arctic sharks. And some of them, like the giant, stealthy Greenland Shark are quite spectacular predators. Who would have expected such toothy monsters lurking beneath the Arctic ice?