New research suggests warm-blooded fish swim faster than those with cold blood.
Scientists already knew some marine species possess a "web" of arteries and veins that allows them to raise their internal temperature to surpass the water they swim in, the University of California - Santa Barbara reported. These new findings show this ability, called endothermy, allows the fish and sharks that have it to swim two and a half times faster and twice as far as those that don't.
"The cost of moving faster and farther is high so there has to be an ecological reason that outweighs the physiological expenditure. These endothermic fishes are putting a lot more energy into each unit of movement than their cold-blooded counterparts are," said UC Santa Barbara research biologist Jenn Caselle. "In fact, the estimated cost of transport is twice as high, but in return they're getting benefits from that increased swimming speed and wider range of migration," she added. "We hypothesize these gains allow these endotherms to be more efficient hunters and to span larger areas in their migration, which probably provides feeding and reproduction benefits."
To make their findings, a team of researchers looked at past data and collected new information using sensors attached to a number of sharks across the globe. The findings showed that warmer "red" muscle endothermy allow for faster swimming and greater endurance. The team hypothesized this feature allowed the species' to take advantage of a greater variety of food sources.
The animals that had the convenient ability included four types of shark and five species of tuna. The researchers believed this fascinating feature developed independently in the distinctive fish groups.
"This research begins to shed light on possible reasons why these endothermic fish evolved in this way," Caselle concluded. "Our paper contains almost every piece of electronically recorded information in the literature right now -- and that's not a lot. We'd like to be able to expand the use of sensor-captured data to other groups of fishes in order to build a dataset we could analyze to see what different species are doing in terms of their movements and speed."
The findings were published in a recent edition of the journal Proceedings of the National Academy of Sciences.