SCIENCE LAB SCALES * : SNAKE KINGDOM

 

Serious Gapes : In the snake kingdom, a small species has a really big mouth.

SNAKES can't really unhinge their jaws, but for some, that doesn't get in the way of swallowing large prey. For instance, Burmese pythons, like the invasive ones making their way north in Florida, have been known to consume 70 pound [32-kilograms] deer, 100-pound alligators.

And new research indicates that, relative to their size, the snakes that can gulp down the largest meals are harmless, three-foot long egg eaters.

'' This particular group of snakes may be No. 1 when it comes to big mouths in the snake kingdom, '' said Bruce Jayne, a biology professor at the University of Cincinnati and the author of a paper on the subject published last month in the Journal Zoology.

The snakes in question, of the genus Dasypeltis,  are found throughout Africa, and they've been primed by evolution for gulping down bird eggs.

They're small, skinny and nearly toothless, since teeth prove to be a hindrance with their food of choice.

'' If you're a generalized snake, with long, thin, pointy teeth and then you're trying to swallow something that is basically like a rock, because it is so hard and unyielding, you're very likely to wind up with a bunch of broken teeth, '' Dr. Jayne said.

While they're pretty useless at hunting non-egg prey, they're very good at what they do. Dasypeltis snakes have specially shaped vertebrae to help crush an egg once it's swallowed, and perhaps most important, special adaptations to their skin and jaws that allow them to open their mouths extra wide.

The lower jaws of snakes are two separate pieces of bone, joined by connective tissue at the ''chin''. This connective tissue, and the skin covering it, are capable of stretching to increase the size of the snake's mouth.

To test the snakes' mouth-opening capabilities, Dr.Jayne measured the maximum open mouth area, or  ''gaps,'' of 15 Dasypeltis gansi egg-eaters and found that Dasypeltis gansi '' has spectacularly stretch skin, enabling it to '' add more than 50 percent of that gape area,'' he said.

A previous study by Dr. Jayne showed that Burmese pythons jaws allow them to expand their gape by 43 percent. Dr. Jayne suspects that Dasypeltis might have the biggest relative gape among snakes.

Bryan Maritz, an associate professor of biology at the University of Western Cape in South Africa, who was not involved in the study, said Dr. Jayne's study stood out because it upended traditional thinking with regard to estimating the size of prey a snake could swallow.

'' We've said, ' Well, gape is correlated broadly with head length, so you can measure a snake's head length and you can estimate its gape, ' '' Dr. Maritz said. '' And this study really shows that that's not the case.'' [ Kate Golembiewski ]