This month we're showcasing a shark who thrives in one of the coldest places on earth. It’s the slowest shark on record, as well as the longest living!

Greenland Sharks belong to a group known as the sleeper sharks. Made up of 17 species, these sharks are named for their slow and sluggish demeanor. Yet, when you live in icy cold waters, life must be taken at a slower pace - conserving energy is vital to your survival. And so it is with the Greenland Shark. Cruising at around 0.34m per second, Greenland Sharks are the slowest shark in the world.

While known to be scavengers, they’re also opportunistic predators and will ambush prey. A short broad tail provides quick bursts of speed, enabling them to catch fast-swimming salmon and seals. But this is rare...

To conserve energy, Greenland Sharks tend to take a craftier approach, sneaking up on prey while they sleep. There have also been reports of Greenland Sharks attacking Caribou as they drink from the banks of river mouths. Scientists even discovered an entire reindeer (including the antlers!) in the stomach contents of one individual. While the remains of polar bears have been found in others!

As their name suggests, they’re native to the North Atlantic and Arctic waters around Greenland, Canada and Iceland. While shark diversity is low in this region, species that live here can grow to an enormous size. And Greenland Sharks are no exception. Reaching over 7m in length, they can weigh over a tonne (1000kg)! This makes them the 2nd largest carnivorous shark after the White Shark.

High concentrations of Trimethylamine N-oxide (TMAO) and urea in their tissues enable them to function in the extreme cold. Acting as an anti-freeze, these chemicals prevent the internal formation of ice crystals and stablilse proteins in their body, which would otherwise stop functioning. It also makes their meat toxic. Yet, the process of fermenting and drying the meat removes the toxins and gives rise to a traditional dish in Iceland known as Hákarl.

Often living in deep dark water, or under ice, Greenland Sharks don’t rely heavily on their sense of sight. This is fortunate because many have copepod parasites attached to their eyes, which renders them partially or completely blind. Even so, it’s speculated that this relationship may be mutually beneficial. Being bio-luminescent, these organisms are thought to help attract prey to the shark.

Animals in polar regions are also known to live a long time. Life moves slower, so everything takes longer. By measuring amounts of the radioactive isotope Carbon-14 (partly a by-product of nuclear bomb detonations) in a shark, scientists can determine their age. Studies have shown that Greenland Sharks live ~400 years, making them the longest-living shark on earth!

Yet, their longevity makes them vulnerable to overfishing. Growing slowly, Greenland Sharks don’t even reach sexual maturity until ~150 years! This means many are caught before they’ve had a chance to reproduce.

These discoveries provided us with a strong case to increase protection for Greenland Sharks. In 2018, working with Shark League partners, we advocated for management at the Northwest Atlantic Fisheries Organisation (NAFO) meeting, where members agreed to ban take from international waters and implement bycatch mitigation measures.

• SCIENTIFIC NAME: Somniosus microcephalus
  
  
• FAMILY: Somniosidae (Sleeper Sharks)
  
  
• MAXIMUM SIZE: 7m
  
  
• DIET: Fish, squid and crab. May also eat land animals and sea birds.
  
  
• DISTRIBUTION: Cold waters of the North Atlantic & Arctic, where temperatures can range from -1°C to 10°C.
  
  
• HABITAT:  Often found in deep, dark water. Or under ice. They’ve been recorded in shallow waters to 2,200m deep.
  
  
• CONSERVATION STATUS: Near Threatened
  
  

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Related Links:

► Check out more incredible sharks and rays covered in our Creature Features

► Discover more fin-tastic facts by visiting our Discover Sharks section