This article is over 5 years old and may contain outdated information.

Wildlife

Shark teeth reveal climate coping strategy

  • Aug 26, 2014
  • 321 words
  • 2 minutes
Researchers collect sand tiger shark teeth on Banks Island, N.W.T. Expand Image
Advertisement

The ferocious-looking sand tiger shark was a much more tolerant species millions of years ago. More tolerant of brackish water, that is.

A study by scientists at the University of Colorado at Boulder, and the University of Chicago has revealed that the prehistoric version of the fish was living in very brackish waters in the Arctic — a finding that may offer some hope for sharks trying to cope with warming oceans today.

Expand Image
A close-up view of a sand tiger shark tooth found on Banks Island, N.W.T. (Photo: Jaelyn Eberle)

Researchers found about 6,000 shark teeth at a coastal site on Banks Island, N.W.T. Teeth determined to be from the early Eocene epoch were compared to those of modern-day sharks. The Eocene was a warm period of about 50 million years ago (when ice was absent from the poles and there were no glaciers) that’s often studied to understand how today’s wildlife might cope with global warming.

“Very little is known about the Arctic Ocean at the time during the Eocene, and we were hoping to study the sharks to get a better sense about the environment,” says Jaelyn Eberle, an associate professor of geological sciences at the University of Colorado at Boulder and co-author of the study.

Analysis of oxygen isotopes in the teeth showed the water the ancient sharks lived in was not at all similar to that of today’s Arctic. “It wasn’t very saline at all. In fact, it was closer to fresh water than it was to salt water,” says Eberle.

The finding suggests that today’s sharks may be able to cope with a warming ocean and subsequent decrease of water salinity. Sand tiger sharks live in ocean waters that are three times as saline as the Eocene Arctic Ocean. “To me this suggests something positive if global warming was to occur,” Eberle says, “because in the past they did OK.”

Advertisement

Are you passionate about Canadian geography?

You can support Canadian Geographic in 3 ways:

Canada in Space

This story is from the October 2014 Issue

Related Content

The spiny dogfish made history when it was certified as the world’s first sustainable shark fishery in 2011

Wildlife

The great green shark hunt 

Can British Columbia’s spiny dogfish make the grade as the world’s first “sustainable” shark fishery?

  • 3319 words
  • 14 minutes

Wildlife

Jawsome: behind the scenes of Canada’s newest great white shark documentary

Korean-Canadian filmmaker Sonya Lee dives deep into the world of great white sharks for the latest documentary from CBC’s The Nature of Things

  • 1781 words
  • 8 minutes

Mapping

COVID-19 vaccine might require compounds from shark liver

Squalene, a compound found in shark liver oil, is a common ingredient used in vaccines to boost the body’s immune response 

  • 1072 words
  • 5 minutes
leather sea stars

Environment

“We did this:” Is there a way out of our intertwined climate and biodiversity crises?

As the impacts of global warming become increasingly evident, the connections to biodiversity loss are hard to ignore. Can this fall’s two key international climate conferences point us to a nature-positive future?

  • 5595 words
  • 23 minutes