Greenland shark

The Greenland shark lives in cold water.

It is a very big shark. It can live for a very long time. This shark can live for hundreds of years!

It stays deep in the ocean. It is a very slow swimmer. It eats fish and seals.

Small sharks eat tiny things like squid. Big sharks eat much larger food.

This shark is a wonder of the sea.

The Greenland shark lives in very cold, deep waters.

It is a giant shark. Some grow to be 6 or 7 meters long. These sharks live for a very long time. They have the longest life of any vertebrate. A vertebrate is an animal with a backbone. Scientists think they live between 250 and 500 years!

These sharks grow very slowly. They do not reach maturity until they are 150 years old. Maturity is when they are old enough to have babies.

Greenland sharks are slow swimmers. They move through the water with very little power. They often hunt by waiting for prey to sleep. They eat many things like fish and seals. They also eat dead animals. They use their jaws to grab food. Their teeth help them hold and cut large chunks.

Some people in Iceland eat their meat. They treat it first to make it safe. This food is called kæstur hákarl. Because they live in deep, cold places, they rarely meet humans.

The Greenland shark is a giant living in the cold North Atlantic and Arctic Oceans.

These sharks are very special because they live for a very long time. They have the longest lifespan of any known vertebrate, which is an animal with a backbone. Scientists estimate they can live between 250 and 500 years. They are also among the largest sharks alive today. Some adults grow to be about 7 meters long. One huge specimen even reached 6.4 meters and weighed a lot.

To survive in deep, freezing water, these sharks have a unique way of working. They move very slowly through the ocean. Their swimming speed is only about 1.2 kilometers per hour. Because they are so slow, they often hunt by ambushing prey while it sleeps. They use a special way to eat by expanding their mouths. This creates suction to pull food inside. Their teeth help them too. The thin teeth in the upper jaw act like an anchor. Then, the broad teeth in the lower jaw cut large chunks of food.

Scientists have studied these sharks to learn about their long lives. In 1936, a shark was tagged near Greenland and found again in 1952. This helped show they grow about 1 centimeter every year. Researchers use radiocarbon dating on the crystals in the shark's eyes to guess their age. This is how they know some sharks are nearly 400 years old. In 2024, scientists even published the shark's genome. This is the complete set of genetic instructions for the animal. It is 6.45 billion base pairs long.

These sharks have a very wide home. They usually like water that is near freezing. They often live in deep water, sometimes over 1,000 meters down. However, they can also be found in warmer places. In 2013, researchers caught one in the Gulf of Mexico. The water there was 25 degrees Celsius. In 2022, a shark was found near Belize on a coral reef. This shows they can live in many different parts of the ocean. They also move up and down in the water to find the right temperature.

Even though they are large, they are not a common threat to people. They live in very deep and remote places. Most people will never meet one in the wild. However, their meat is famous in a different way. The meat contains high levels of a substance called trimethylamine N-oxide. This makes the meat toxic to mammals if eaten raw. In Iceland, people make a special food called kæstur hákarl. They treat the meat first to make it safe to eat. It is a very pungent delicacy.

The Greenland shark, known scientifically as *Somniosus microcephalus*, is a massive species of shark. It belongs to the Somniosidae family, which includes other "sleeper sharks." These sharks inhabit the cold waters of the North Atlantic and Arctic Oceans. They are famous for their incredible longevity. In fact, they have the longest lifespan of any known vertebrate. Scientists estimate they can live between 250 and 500 years.

To survive in freezing, deep environments, these sharks have unique biological adaptations. They are ectotherms, meaning their body temperature follows the water around them. Because they live in water near freezing, they are very sluggish. They have the lowest swim speed and tail-beat frequency for their size among all fish. Their average speed is only 1.2 kilometers per hour. This slow movement is likely linked to a very slow metabolism. This metabolic pace helps them achieve their extreme lifespans.

Feeding is a specialized process for these apex predators. They are generalist feeders, meaning they eat many different things. They consume fish like cod, halibut, and salmon, as well as seals and even minke whales. They also act as scavengers, eating carrion or rotting meat. To eat large carcasses, they use a rolling jaw motion. The 48 to 52 teeth in the upper jaw are thin and pointed. These act as an anchor for the prey. Then, the broad, square teeth in the lower jaw interlock to cut large chunks.

Their internal chemistry also helps them handle the deep ocean. Greenland sharks have high concentrations of urea and trimethylamine N-oxide, or TMAO, in their tissues. These nitrogenous compounds increase buoyancy. TMAO also acts as an osmoprotectant. It helps protect their proteins from being destabilized by urea and high deep-water pressure. Their blood contains three major types of hemoglobin. These proteins help carry oxygen. These specific hemoglobins have a lower affinity for oxygen than temperate sharks. This is another adaptation for life at great depths.

Researchers have learned much about these sharks through history and genetics. In 1936, a shark was tagged near Greenland and recaptured in 1952. This showed they grow at a rate of about 1 centimeter per year. Scientists estimate their age by using radiocarbon dating on crystals in their eye lenses. In 2024, the shark's genome was published. It is 6.45 billion base pairs long. This data helps scientists study how they live so long. They are looking at how certain genetic elements might play a role in their aging.

While they are huge, they are not a common threat to humans. They live in deep, remote areas. One possible attack on British fishermen occurred in August 1936, but it was never identified. However, their meat is quite special. It contains high levels of TMAO, which makes it toxic to mammals. In Iceland, people eat a treated version called kæstur hákarl. This is a pungent delicacy.

Greenland sharks also have interesting relationships with other creatures. They are often infested by a crustacean called *Ommatokoita elongata*. This parasite attaches itself to the shark's eyes. This can cause damage like ulceration or even blindness. Interestingly, this does not seem to reduce their lifespan. The sharks rely heavily on smell and hearing to hunt. Some scientists think the parasite might even help the shark by using bioluminescence to attract prey. This is a theory called a mutualistic relationship, though it is not yet verified.

Finally, these sharks have a much wider range than once thought. They typically prefer water near 0 degrees Celsius at depths of 200 to 700 meters. However, they have been found in the Gulf of Mexico at 25 degrees Celsius. They have even been spotted near coral reefs in Belize. They migrate annually based on temperature and depth. During winter, they move to shallower waters for warmth. In summer, they migrate to deeper areas. This movement helps them navigate the changing Arctic and Atlantic ecosystems.