Greenland sharks: The longest-living vertebrates

Greenland sharks (Somniosus microcephalus) belong to a household of sharks known as sleeper sharks, which go and stealthily by the water. They are the longest-living vertebrates, or animals with backbones, surviving for up to hundreds of years within the deep, cool waters of the Arctic and North Atlantic oceans. 

These sharks sneak up on reside prey and scavenge needless animals, including other sharks, seals, drowned horses and polar bears. Scientists are studying increasingly extra about these mysterious sharks that now not regularly locate participants, but there are light many unknowns surrounding their existence. 

How huge are Greenland sharks?

Greenland sharks are among the many most interesting sharks within the realm; they grow up to 24 feet (7.3 meters) prolonged and weigh up to 2,645 pounds (1,200 kilograms), in accordance with the St. Lawrence Shark Observatory (ORS). That’s longer than colossal white sharks (Carcharodon carcharias), which are estimated to grow up to 20 feet (6 m) prolonged, with unconfirmed stories suggesting they’ll reach 23 feet (7 m) in length, in accordance with the Florida Museum of Natural History. 

Greenland sharks rep cylindrical bodies that may possibly possibly presumably even be sunless, brown, gray or a mixture of all three colours, and they’ll even rep spots. These sharks even rep teeth-treasure scales, known as dermal denticles, covering the surfaces of their bodies. The scales decrease scuttle and back the sharks switch extra silently by the water, in accordance with the ORS. A Greenland shark’s mouth comprises 48 to 52 teeth in its greater jaw and 50 to 52 teeth in its decrease jaw. The upper teeth are pointed, to back the sharks retain on to bigger meals, while the decrease teeth are broad and crooked sideways so the sharks can prick out spherical chunks of flesh from prey by transferring their head in a spherical inch, in accordance with the ORS.

Ocean parasites known as Ommatokoita elongata are generally linked to the eyes of Greenland sharks. The parasite tends to reside in precisely one of the most shark’s eyes, but this must render the shark partly blind. Because the sharks depend extra on their other senses to defend cessation prey within the needless of night time ocean waters, the parasites assemble now not seem to electrify the sharks powerful, in accordance with the Florida Museum of Natural History. 

Connected: Historical Greenland shark unearths its age in eerie underwater video

How prolonged cessation Greenland sharks reside?

Greenland sharks’ valid lifestyles span is unknown, but they’re belief of because the longest-living sharks, and the longest-living vertebrates, within the realm. A 2016 seek of the sharks’ concept tissue revealed within the journal Science estimated that Greenland sharks rep a maximum lifestyles span of a minimal of 272 years. Researchers estimated that the oldest Greenland shark in that seek became as soon as about 392 years weak, but the estimate had a swish margin of error of 120 years, which led to hypothesis that Greenland sharks may possibly possibly reside to 512 years weak. The estimated vary hasn’t been verified.

“It be vital to withhold in mind there’s some uncertainty with this estimate,” Julius Nielsen, co-creator of the 2016 paper, previously told Reside Science. “However even the bottom fragment of the age vary — a minimal of 272 years — light makes Greenland sharks the longest-living vertebrate known to science.”

Greenland sharks reside within the listless lane, with a top swimming tempo of now not up to 1.8 mph (2.9 km/h). Besides they grow slowly at now not up to 0.4 walk (1 centimeter) per Twelve months and rep listless metabolisms, in accordance with the Nationwide Oceanic and Atmospheric Administration (NOAA). Scientists assemble now not but know the diagram Greenland sharks reside goodbye but it must also very properly be linked to their listless reach of lifestyles.  

Connected: No, scientists haven’t chanced on a 512-Twelve months-weak Greenland shark

The keep cessation Greenland sharks reside?

Greenland sharks reside within the Arctic and North Atlantic oceans from North The united states to Greenland and from Portugal to the East Siberian Sea, in accordance with the World Union for Conservation of Nature (IUCN). The sharks rep a swish vary and may possibly possibly presumably even be chanced on swimming from the bottom the total model down to depths of 8,684 feet (2,647 m), the IUCN says. 

Scientists light rep powerful to learn about how Greenland sharks reside and reproduce. Feminine Greenland sharks give beginning to reside younger, known as pups, that hatch from relaxed eggs that the females raise inner their bodies. In a 2020 seek revealed within the journal PLOS One, researchers estimated that Greenland sharks give beginning to between 200 and 324 pups per pregnancy, reckoning on the size of the shark. Greenland shark pups are real 14 to 18 inches (35 to 45 centimeters) prolonged after they’re born. 

What cessation Greenland sharks use?

Greenland sharks rep a various diet that involves fish, other sharks, eels and marine mammals, akin to seals. They rep also been chanced on with drowned land animals, including horses and reindeer, in their stomachs, and had been considered in swish numbers at the ocean ground, feeding collectively on the stays of whales and fish killed correct by commercial whaling and fishing, in accordance with the College of Michigan’s Animal Vary Web (ADW). 

Scientists chanced on a Greenland shark with the jaw of a younger polar rep (Ursus maritimus) in its abdominal, Reuters reported in 2008. The researchers had been now unsure the diagram it acquired there; but most shark consultants believed that the polar rep became as soon as seemingly already needless when the shark ate it, as reside polar bears are too unhealthy for the sharks to take cling of on. Researchers also chanced on some polar rep muscle tissue and pores and skin within the abdominal of 1 other Greenland shark correct by a 2014 seek revealed within the journal Polar Biology, and they concluded that the rep became as soon as seemingly scavenged quite than hunted.  

Greenland sharks are reach the tip of the meals chain, but sperm whales (Physeter macrocephalus) may possibly possibly hunt them. Chris Harvey-Clark, co-founding father of the Greenland Shark and Elasmobranch Training and Learn Crew (GEERG, now the ORS), wrote in Capeia, a web science verbal change magazine, about recording a Greenland shark seemingly fleeing from the echolocation clicks of a foraging sperm whale. Upon its death, that sperm whale became as soon as chanced on with its teeth outmoded the total model down to stumps, such as those of orcas (Orcinus orca) that feed on Pacific sleeper sharks (Somniosus pacificus), which are closely connected to Greenland sharks and rep similarly tricky pores and skin. As such, Harvey-Clark theorized that the sperm whale hunted Greenland sharks. Scientists are but to appear sperm whales looking these sharks someplace else.

Connected: Sperm whales outwitted 19th-century whalers by sharing evasive ways

Are Greenland sharks unhealthy?

There are now not any verified stories of a Greenland shark attacking a human. Then as soon as more, some anecdotal evidence suggests that such assaults may possibly possibly occur. GEERG divers noticed a Greenland shark “stalk” a team of divers. They rep also considered Greenland sharks investigate diver actions as within the occasion that they had been scouting seal prey, in accordance with the ORS. A Greenland shark became as soon as reportedly chanced on with a human leg in its abdominal off Canada’s Baffin Island spherical 1859, but this narrative became as soon as now not verified.

Untreated Greenland shark meat is toxic to participants, because it comprises excessive ranges of trimethylamine oxide (TMAO), which breaks down into the toxic trimethylamine (TMA) compound correct by digestion, in accordance with a 1991 seek revealed within the journal Toxicon. TMA can trigger extreme intestinal problems and produces connected effects to rude alcohol consumption. Greenland shark meat is edible handiest when dried. The dried meat is fed to sled canines in northern regions akin to Greenland, in accordance with the Florida Museum of Natural History. The shark can even be fermented and consumed as a delicacy in Iceland.

Are Greenland sharks endangered?

The IUCN considers Greenland sharks to be at risk of extinction. Humans killed Greenland sharks for his or her liver oil to make use of in lamps and other merchandise between the 13th and 20th centuries. The commercial fishing of Greenland sharks for his or her oil ended by the 1960s, which helped their population. Then as soon as more, Greenland sharks proceed to be caught and killed as bycatch, or animals that discover pulled up by fishers alongside their intended defend cessation, as an example, in swish nets dragged along the bottom of the ocean intended to defend cessation a swish assortment of fish. Most of the Greenland sharks eaten by participants and fed to canines advance from bycatch, though some sharks are targetted on a little scale.  

The Northwest Atlantic Fisheries Group (NAFO), an intergovernmental fishing science and administration body, prohibits the explain fishing of Greenland sharks and seeks to decrease bycatch. The NAFO applies to most fisheries within the Northwest Atlantic ocean and involves countries such because the U.S. and Canada. The IUCN recommends extra protections, akin to bycatch coverage, be developed for Greenland sharks and enforced. 

The IUCN estimates that the Greenland shark population has declined by 30% to 49% over the past 450 years, or three shark generations. Then as soon as more, this decline became as soon as estimated in keeping with a conservative Greenland shark lifestyles span of 150 years; the decline will be powerful bigger if the sharks rep longer lifestyles spans, because it would take cling of them longer to place reproductive age and create extra sharks. The world Greenland shark population dimension is unknown. Climate change can even be hurting the species — as an example, by reducing Arctic sea ice, which gives fishing fleets more straightforward discover entry to to Greenland shark habitat. 

Extra sources

• Gaze footage and videos of a Greenland shark and other deep sea creatures encountered correct by the NOAA Northeast U.S. Canyons Expedition in 2013.  
• Gaze this rapid video on YouTube about how Greenland shark meat is though-provoking and consumed in Iceland, from Meals Insider.
• Learn extra about the keep Greenland sharks reside with an interactive blueprint, from the Encyclopedia of Lifestyles. 

Patrick is a staff creator for Reside Science. His background is in natural world conservation and he has labored with endangered species across the realm. Patrick holds a master’s stage in world journalism from Cardiff College within the U.K. and is currently finishing a second master’s stage in biodiversity, evolution and conservation in inch at Middlesex College London.