Sharks outlasted the dinosaurs, so it's fitting that they have the potential to tell us quite the story about Earth's climate. Fortunately, getting that won't require messing with them.
Evolutionary biologist and Caltech postdoc Rob Eagle along with his colleague Aradhna Tripati, an assistant Earth sciences professor at UCLA, have discovered a direct link between shark teeth and ocean temperatures.
The scientists knew from previous research by Caltech professor John Eiler that it was possible to figure out the temperature at which a mineral forms by looking at the chemical bonding between two rare isotopes of carbon and oxygen. Cold-blooded sharks have the same body temperature as the water where they live. The scientists wondered if it was possible to calculate that water temperature from a mineral in shark teeth called apatite.
Sharks regularly lose a tooth from their barbed jaws, so the scientists obtained naturally discarded teeth. "We’re getting teeth from sharks that had lived in aquariums at different temperatures to see if this was reflected in the chemical composition of their teeth," Eagle says. "Remarkably it was." He and Tripati are currently preparing to publish their findings.
Between 40 and 60 million years ago, carbon dioxide levels were thought to be much higher on Earth than they are now. Measuring shark teeth could be a way to find out exactly how hot the oceans actually were, Eagle suggests. And it could tell us more about what is happening in the oceans now. The scientists plan to examine samples from wild sharks next. "This is all pretty new really," Eagle says. "This is the first time people have looked at teeth like this."
Photo: A tiger shark at KLCC Aquaria in Kuala Lumpur. Credit: Miusam Saleem.
Tags: Carbon Emissions, Conservation, Evolution, Green Tech, Water
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