Greenland sharks are one of the largest sharks and may be the longest living vertebrate on the planet. Also known as sleeper sharks, their scientific name Somniosus microcephalus, roughly translates to “sleepy small head.” These sharks swim slowly, reaching a top speed of only 1.8 mph (2.9km/h) and grow slowly, averaging less than .4 “ (1 cm.) per year. Their maturity rate is so sluggish, in fact, that scientists think they don’t start reproducing until they’re about 150 years old — and that they can live anywhere from 270 to 500 years. Preferring cold, deep waters, they are found in the Arctic around the North Pole, around Greenland, northern Canada and Denmark.
At-A-Glance
Scientific Name – Somniosus microcephalus
Size – Averaging 8-14ft/4.2m, but can reach up to 23ft/7m.
Habitat – Found in cold waters within the Arctic Ocean and North Atlantic. They are infrequently seen at the surface and can live at depths up to 7,200 ft (2,195.56 m) and between 28.4 to 44.6 degrees F (-2 – 7 degrees C).
Diet – Different types of fish including smaller sharks, crustaceans and sometimes mammals.
Reproduction – Ovoviviparous – mate using internal fertilization, eggs are retained within the body and give birth to live young with litters of up to 10 pups. The young are born at a size of 15in/38cm. Females do not reach sexual maturity until they are 150 years old.
IUCN Listing – Vulnerable.
Protection – The Northwest Atlantic Fisheries Organization (NAFO), an intergovernmental organization that manages fisheries, has prohibited the retention of Greenland sharks in international waters. The new rule would prohibit intentional fishing or the keeping of Greenland sharks accidentally caught as bycatch. Exceptions would be possible if countries have a domestic ban on discarding fish, as is the case in Iceland, Norway, the Faroe Islands and Greenland. However, such exceptions would only apply to the accidental catching of the sharks — not to deliberate fishing.
Bet You Didn’t Know…
- Greenland sharks are opportunistic feeders, eating just about any meat they find- dead or alive. While most of their diet consists of squid, fish and seals, scientists have also found the remains of polar bears, moose and reindeer in their stomachs.
- Most Greenland sharks are nearly blind due to parasites called copepods that affix themselves to shark’s cornea. Since there isn’t much light in the depths of the ocean, vision is less important than their other senses in finding prey.
- The meat of Greenland sharks is toxic to humans as it contains high levels of trimethylamine oxide (TMAO) which can cause severe intestinal issues. To make it safe for consumption, the meat must be left to rot, compressed to remove the toxins then dried for months. The result is an Icelandic delicacy known as Hákarl.
Ready To Dive In?
March-April, Greenland, near icebergs in pack ice and under ice in the Artic. Experienced cold water divers since water temps are 26°F to 30°F/ -1°C to -3°C. Burrr that’s cold!
Science In The Spotlight
Radiocarbon dating is used to age objects ranging from animals to rocks. In the mid-1900s bomb testing left radioactive signatures in the atmosphere, waters, and soils. Animals born during this time have a signature in their tissues. Animals born before this time do not. In the middle of the eye, there is a protein that is formed before birth. This is where scientists look for the bomb signature, and to determine age.
Eye lens radiocarbon reveals centuries of longevity in the Greenland shark