Shark secrets
Keeping ones mouth shut? Even the sharks know this, if we are to believe David Sims of the University of Aberdeen in the uk . According to Sims, basking sharks know when to keep their mouth shut, while they cruise the coast. He has also calculated that sharks need to keep their mouths shut when there is less than 0.55 gm of plankton per cubic metre. Below this, sharks would not recoup the extra energy needed to swim with an open mouth ( Proceedings of the Royal Society B , Vol 266, p1, 437).