One of the last things biologists expected to find in the balmy Caribbean Sea was an ancient Greenland shark, a creature known for its distant sojourn in the icy Arctic.
Still, while temporarily capturing and tagging tiger sharks off the coast of Belize, researchers caught a Greenland shark (or possibly a Greenland shark hybrid), a species that has been alive for ages in the deep sea.
“We suddenly saw a very slow-moving, sluggish creature below the surface of the water,” Devanshi Kasana, a biologist and Ph.D. candidate in Florida International University’s Predator Ecology and Conservation lab, Mashable told me. The sighting was recently published in the scientific journal marine biology. Initially, the researchers thought it might be a six-gill shark, a dominant and fascinating predator of the deep sea. But they photographed the rarely seen animal and confirmed it was a Greenland shark.
“It looked like something that would exist in prehistoric times,” Kasana added.
There is a fascinating new clue to the extinction of the giant megalodon
Greenland sharks do indeed belong to a family of sharks that are about 100 million years old and that existed when dinosaurs dominated the planet. The sharks spend much of their lives in the dark, thousands of feet underwater, where they grow slowly, move slowly and age slowly. Down in the deep sea, where nutrients are scarce, moving slowly to conserve energy is an important adaptation. Greenland sharks are clearly well adapted to these depths: they live for more than two and a half centuries, and perhaps considerably more. They are the longest-living vertebrate on Earth.
The Greenland shark, with its stark green-blue eye, sighted in Belize by marine biologists.
Credit: Devanshi Kasana
What is a Greenland shark doing in the Caribbean?
Spotting a Greenland shark off a coral reef off the coast of Belize was certainly an unexpected surprise. But it is not inconceivable.
This relatively little-known species is known to thrive in the deep seas in and around the Arctic. They could potentially live in other deep ocean regions as well, biologists say. This includes the Caribbean. After setting a line in Belize’s protected Glover’s Reef Atoll while observing and researching tiger sharks, the biologists returned the next day and found their line was a few miles from the coral reef, in water some 2,000 feet deep.
When they retrieved their scientific catch, they spotted the unusual shark. “It looked very, very old,” amazed Hector Daniel Martinez, one of the researchers who saw the shark and a co-author of the study. “It was in very deep water.”
“It looked very, very old.”
The slope of the nearby reef drops to some 9,500 feet deep. It’s a deep cold, dark realm, ideal for a Greenland shark.
The deep seas are famously little explored and misunderstood. The discovery of this Arctic shark underscores that just because we haven’t seen a phenomenon doesn’t mean it doesn’t occur. “We know so little about the deep ocean that pretty much anyone can find something new if they do something unique there,” Alan Leonardi, the director of the National Oceanic and Atmospheric Administration’s Office of Ocean Exploration and Research, told Mashable in 2020.
Finding a Greenland shark in Belize wasn’t easy. It required several researchers, local fishermen and the government of Belize to work together in a protected area of the ocean. It gave researchers the opportunity to observe something scientifically unprecedented. “This discovery was made possible by scientists working together,” said Demian Chapman, one of the study’s co-authors and director of Sharks and Rays Conservation Research at Mote Marine Laboratory and Aquariumtold Mashable.
“It was very close to coral,” Chapman noted. “Normally you think they’re close to ice.”
A looming question is whether this particular Greenland shark traveled from the Arctic seas to the Caribbean, or whether it has lived much of its life in (deep) tropical waters. It is unknown. But chances are there are more of them roaming out there, in the dark waters where we can’t see anything.
“I doubt it’s the only one,” Chapman said.