Νέα

• News in English
• 15/10/2021

Greenland sharks: The longest-living vertebrates

A Greenland shark swimming in the St. Lawrence River estuary in Canada. Greenland sharks (Somniosus microcephalus) belong to a family of sharks called sleeper sharks, which move slowly and stealthily through the water. They are the longest-living vertebrates, or animals with backbones, surviving for up to hundreds of years in the deep, cold waters of the Arctic and North Atlantic oceans. 

These sharks sneak up on live prey and scavenge dead animals, including other sharks, seals, drowned horses and polar bears. Scientists are learning more and more about these mysterious sharks that rarely encounter humans, but there are still many unknowns surrounding their lifestyles. 

Greenland sharks are among the biggest sharks in the world, they grow up to 24 feet (7.3 meters) long and weigh up to 2,645 pounds (1,200 kilograms), according to the Greenland sharks have cylindrical bodies that can be black, brown, gray or a mixture of all three colors, and they may have spots.

These sharks also have teeth-like scales, called dermal denticles, covering the surfaces of their bodies. The scales reduce drag and help the sharks move more silently through the water, according to the ORS. A Greenland shark’s mouth contains 48 to 52 teeth in its upper jaw and 50 to 52 teeth in its lower jaw. The upper teeth are pointed, to help the sharks hold on to larger food, while the lower teeth are wide and curved sideways so the sharks can carve out round chunks of flesh from prey by moving their head in a circular motion, according to the ORS.

Ocean parasites called Ommatokoita elongata are often attached to the eyes of Greenland sharks. The parasite tends to live in just one of the shark’s eyes, but this can still render the shark partially blind. Because the sharks rely more on their other senses to catch prey in the dark ocean waters, the parasites don’t seem to affect the sharks much, according to the Florida Museum of Natural History.