Hot great white sharks could motor but prefer to swim slow
Yuuki Watanabe has always been fascinated by speed and power. As a child, he recalls being transfixed by the raw strength of great white sharks (Carcharadon carcharias). 'They look cool' says Watanabe, from the National Institute of Polar Research, Japan. However, he now has another reason for being in awe of these charismatic predatory sharks: 'they are an endothermic fish', he says. In other words, they maintain a warmer body temperature than the surrounding water—in contrast to most fish, which simply go with the thermal flow. This relatively warm-bodied lifestyle should allow them to swim at much higher speeds than their cold-blooded contemporaries. Yet, no one had successfully recorded the great white's behaviour to find out how their relatively warm lifestyle influences their activity. Would their warm muscles allow them to live up to their high-speed reputation? It turns out that although the fish could swim fast, they opt for...