How snakes stay skinny

Snakes can lower their metabolic rates by up to 70 per cent, allowing them to survive prolonged (longer) periods without food while growing longer nonetheless, a new study shows. "These animals take energy reduction to a whole new level," said lead author Marshall McCue, a biology graduate student at the University of Arkansas.

The research, detailed in the September issue of the journal Zoology, is an extension of McCue's past studies that revealed biochemical changes in the western diamondback rattlesnake.

McCue withheld food from 62 snakes belonging to one of three different species (ratsnake, western diamondback rattlesnake and ball python) for about six months and observed their metabolic rates. It is typical for snakes in the wild to go without food for this long.

He found that snakes reduced their standard metabolic rates, some by up to 72 per cent. "Snakes already had low energy demands. We didn't know they could go lower," McCue said.

Despite the lack of food, the snakes continued to grow in length. "To me, this suggests that there must be a strong selective advantage to growing longer," McCue said. He added evolution has led to snakes that are extremely efficient at frugal (thrifty) use of available resources which come from within their own bodies.

During the first stages of starvation, all the snakes burned up selected fat stores. The next energy source to go differed among the snake species. The rats snakes, which live in an environment with abundant rodent prey, began to break down proteins faster than the pythons or rattlesnakes.

"The protein use was higher in the snakes less well-adapted to starvation," McCue said.

Understanding how snakes can succeed in food-scarce environments will add to the overall picture of snakes' evolution.

LiveScience.com