BASKING sharks know when to keep their mouths shut as they cruise around the coast, according to a biologist in Britain.
The gentle giants filter tiny plankton from seawater, but their gaping mouths increase drag. David Sims of the University of Aberdeen calculated that the sharks should keep their mouths shut when there is less than 0.55 grams of plankton per cubic metre. Below this, the animals would not recoup the extra energy needed to swim with an open mouth.
Tracking a feeding group of the fish, Sims found that their behaviour matched his model (
To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content.