The Greenland shark (Somniosus microcephalus), also called boreal shark, is a shark that belongs to the genus Somniosus, a group made up of several species known as sleeper sharks. This animal, despite its name, also inhabits other marine areas other than those of the kingdom of Denmark. Currently, there are several management plans to conserve this species due to its population decline. In addition, this animal has a very peculiar characteristic, since it is one of the longest-lived vertebrates on earth.
Continue reading this page on our site and find out how many years this cartilaginous fish called Greenland shark,can live, as well as many other facts interesting.
Characteristics of the Greenland Shark
The Greenland shark is a shark of large size and can measure 6 meters or more in length. longitude, with the peculiarity that it grows only approximately one centimeter per year. The weight is around the ton, although it can exceed this number. The coloration can be a not so intense gray tone or brown, possibly presenting stripes or spots that vary in intensity on the background color. As for the skin, it is quite rough due to the presence of dermal denticles.
The Greenland shark is stocky, cylindrical in shape; its snout is short and with a rounded tip. Both jaws have multiple rows of teeth, but they are different in shape. The upper ones are sharp, while the lower ones have a cutting function. The precaudal fins are small. For its part, the dorsal fins are symmetrical and although the caudal fin is present, it lacks the anal fin.
How many years can a Greenland shark live? The peculiar characteristic of this shark is its longevity According to a recently published study [1], life expectancy is 272 years for this species. However, one of the specimens studied was 392 ± 120 years old, which led to the conclusion that the Greenland shark is the longest-living vertebrate within biodiversity animal. Some researchers [2] claim to be more conservative in this regard and opt for an average figure of around 150 years of longevity. However, there is no doubt, it is an animal with a high life expectancy.
On the other hand, this shark develops a partial blindness due to the parasitic relationship it establishes with a species of copepod, which is It feeds on the tissue of the cornea, which makes it partially lose its vision, so that it is limited from this point of view. But sharks have different sensory mechanisms to develop optimally in the sea.
Greenland Shark Habitat
The habitat of this species is located in Marine ecosystems of the North Atlantic, from the United States, Canada to Greenland. Also from Portugal to an area of the Arctic Ocean and the East Siberian Sea. Its depth range varies from the surface to approximately 2,600 meters. However, in some areas it prefers to be between 300 and 500 m.
Water temperatures in which the Greenland shark is usually found are between 1 and 12 oC in coastal, pelagic and demersal ecosystems. It also moves to intertidal zones and estuaries. Without a doubt, it is a species that moves through northern polar ecosystems.
Greenland Shark Customs
The Greenland shark tends to have a rather slow swim. It has a lonely behavior, except at mating time or casual gatherings that occur in areas where food is concentrated. It spends most of its time foraging for food, so it is an active hunter despite its slow pace.
There are no reports of attacks on people, so it is not usually considered an aggressive species in this sense. However, this could also be due to the fact that in the waters where it usually transits it is very rare to coincide with humans, so caution is always important.
As for its mobilizations, in summer it tends to move towards coastal areas, while in winter it moves out to sea.
Greenland Shark Feeding
As we mentioned earlier, the Greenland shark actively forages for its food, which is mainly made up of varioustypes of fish , marine mammals (seals, walruses and small whales), molluscs, crustaceans, echinoderms and cnidarians. It is also a scavenger species , which concentrates in places of accumulation where the fishing industry leaves traces of its activity. It is also known that it can feed on large animals that are dead, injured or trapped in the ice.
Something that has caused curiosity is that, being this animal quite slow, it feeds on species that swim quickly. Given this, the copepod that settles in its eyes is luminescent, which serves to attract its prey and capture it. However, studies confirming these data are lacking. On the other hand, it is known that these sharks have an excellent sense of smell,general characteristic of these fish, an advantage that makes them efficient when hunting.
Greenland Shark Breeding
Male males mature at 2.5 meters, while females mature at 4 m approximately, which corresponds to a little more than 150 years It is a species ovovivípara, is also referred to as lecithotrophic viviparous, since the young, although they develop inside the mother, are nourished by the egg in which they are found.
Females gestate between 2 and 10 pups that at birth measure between 40 cm and 1 mDue to the lack of specific studies, there are only estimates in some aspects. For example, the young become independent as soon as they are born. Reproduction is every two years, as in the case of other sleeper sharks.
Conservation status of the Greenland shark
It has been a species hunted for centuries to use the oil from the liver, the skin and the marketing of the meat despite its slight toxicity to people if not treated properly beforehand. Currently, the main threat is due to its incidental capture in fishing nets for other species.
The International Union for Conservation of Nature (IUCN), has declared the Greenland shark as vulnerable, with a declining population trend. Among the main conservation actions, hunting has been limited in various regions, as well as the mandatory release with the least possible damage in case of incidental captures.
