Researchers from all over the world have been diving into the remarkable life of the Greenland shark. This incredible animal can reach lengths in excess of 20 feet and boasts a remarkable lifespan of anywhere between 100 and 500 years. This remarkable species has potentially witnessed significant historical events, living during the eras of influential figures such as William Shakespeare and Galileo. For an animal so long-lived, there’s still a good deal we don’t know about the Greenland shark.
Recent studies have revealed that the Arctic region, where these sharks thrive, is warming at an alarming rate. This is faster than any other area on Earth. Such drastic shifts force us to consider what environment these sharks claim as home and how they’re adapting to thrive there. Researchers are particularly focused on understanding the species’ behavior and movement patterns, which appear to be more complex than previously understood.
Greenland sharks prove the use of the undersea ninja approach. They manipulate their end fins to achieve incredibly precise movements in the water. They’ve even been observed plunging directly from the water’s surface to the seafloor. This shows a far wider latitude for action than we could have imagined. Only people with thousands of dollars to spare can fly great distances. Indeed, evidence has even indicated that a single shark could travel the full breadth of the Atlantic Ocean over its lifetime.
That’s why the name “Greenland shark” can be misleading. Despite being sometimes associated with the cold waters of Greenland, these sharks can be found in the tropical waters of the warm Caribbean. This trend is not one of them being ‘lost’, but indeed of their newfound promise as global circumnavigators.
Though the largest and most capable singers on earth, little is known about their breeding behavior. Only the second time ever have scientists observed a pregnant female Greenland shark since 1950. To this day, they don’t have some of the most basic information like where these sharks give birth, or how many pups they typically have in a litter. Researchers argue that getting at these questions is important for advancing science and critically important for informing conservation priorities.
Besides their secretive reproductive practices, Greenland sharks are thought to be ambush predators. And they can ambush sleeping mammals or hunt for breathing holes in the ice. Such behavior is typical of their predatory efficiency and further mutes misconceptions we tend to have about their diets. Some of you may consider them to be scavengers. Contrary to expectations, research indicates they are more effective hunters than we knew.
“I think they’re tricky, I think they’re sharp and suspect they’re actually very capable predators,” – Nigel Hussey
Greenland shark with cloudy eyes and annoying parasitic copepods hanging onto it. Yet, their retinas are immaculate, able to pick up light and contrast with incredible precision. This remarkable anatomical feature only prompts more questions about how they find their way around their pitch-black, icy haunts.
The research community is all too aware of the challenges in studying a species so enigmatic by nature.
“This type of dating method is challenging to use for ageing animals that are hundreds of years old,” said Nigel Hussey. “In some ways, it was a surprise the paper was published in Science, one of the top tier ecology journals in the world. The technique requires further validation for use in this context.”
In the scientific community, there is already recognition that they have only begun to fit together a very incomplete picture of Greenland sharks.
“Studying Greenland sharks is like finding a handful of puzzle pieces,” said Eric Ste Marie, “but then realizing it’s a thousand-piece puzzle.”
This yet-to-be published research further highlights just how scarce existing data is. As one researcher noted:
“We’re taking blind shots in the dark. We have so little data that we make a hypothesis based on what we know, but need so much more research to fully understand what’s actually going on with these sharks.”
The most important questions about their migration routes, wintering grounds and breeding habits are still out there.
“Even if they live only 100 years, how far can they travel in that time? How big does our scale of management need to be?” asked Jena Edwards.
Researchers ponder whether it is necessary to consider that a single Greenland shark could be moving across the entire Atlantic Ocean throughout its life.
“Do we need to consider that one animal is likely moving across the whole of the Atlantic Ocean in its lifetime?” – Jena Edwards