Image: NOAA Okeanos Explorer Program (Public domain)
1. They are Earth’s longest-living vertebrates
Researchers used radiocarbon dating to determine the ages of 28 of the Greenland female sharks, and estimated that one female was around 392 years old (392 ± 120 years and was consequently born between 1504 and 1744)—and 27 others with an average age of 272 years old. The study published in the Journal Science."Our lifespan study is based on the carbon-14 dating of Greenland shark eye lenses. As with other vertebrates, the lenses consist of a unique type of metabolically inactive tissue. Because the center of the lens does not change from the time of a shark's birth, it allows the tissue's chemical composition to reveal a shark's age. We use well-established radiocarbon methods, but combine them in a new way. This approach, along with the extraordinary ages for these sharks makes this study highly unusual," according to Julius Nielsen.
The Greenland shark has the longest known lifespan of all vertebrate species on Earth.
2. They grow slowly
Greenland sharks can grow to be up to 24 feet (7 meters) long and weigh up to 2,645 pounds (1,200 kilograms), according to the Greenland Shark and Elasmobranch Education and Research Group (GEERG). But they grow slowly, at an average rate of 1 cm in a year. The females are bigger than the males.3. It takes around 150 years to reach sexual maturity
The mouse reaches sexual maturity within 6–8 weeks and has a lifespan of 2–4 years, whereas for the Greenland shark it takes around 150 years to reach sexual maturity but then its lifespan exceeds 400 years.4. Slow and steady wins the race
The Greenland shark is one of the slowest swimming sharks in the world and is sometimes called the sleeper sharks. They tend to only move at 0.76 mph (0.3 m/s).5. They like cold water
Greenland sharks are rarely seen because they prefer to live in deep, cold water. They prefer to stay in cold water ranging from -1 to 10°C (30.2 to 50°F)6. They can go deep
Greenland sharks found anywhere between the sea surface and depths of 2,200 meters (about 7,200 feet).In August 2013, researchers from Florida State University caught the first documented Greenland shark in the Gulf of Mexico at a depth of 1,749 m (5,738 ft), where the water temperature was 4.1 °C (39.4 °F).
7. Their flesh is poisonous
Greenland shark meat is toxic to humans. The shark’s flesh contains high levels of uric acid and trimethylamine oxide. The mixture of both chemicals acts as a natural anti-freeze to protect the shark from the frigid arctic waters.If the meat is eaten without pretreatment, the ingested TMAO is metabolized into trimethylamine, which can produce effects similar to extreme drunkenness. Greenland shark flesh treated to reduce toxin levels is eaten in Iceland as a delicacy known as kæstur hákarl.
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