This egg-eater may have the biggest gulp of any snake its size

Its mouth can surround bigger prey than any other snake having a similar weight or length

Hulking hunters like Burmese pythons may be famous for scarfing up deer, alligators and other giant prey. But one little African snake make take the title for most outsized meals. The nonvenomous and nearly toothless Dasypeltis gansi can open its mouth wider than any other snake its size.

Biologist Bruce Jayne shared the new finding August 8 in the Journal of Zoology.

D. gansi, sometimes called the Gans’ egg-eater, swallows bird eggs whole. To get the good stuff inside that egg, the snake cracks the shell with its spine. Then, it ingests the egg’s gooey contents and spits out the empty shell.

On the left, a large snake appears with a cylinder inside its mouth, while a small snake appears on the right with a cylinder inside its mouth.
The biggest Gans’ egg-eater that biologist Bruce Jayne inspected (left) was about 94 centimeters (37 inches) long. It could wrap its mouth around a cylinder 5 centimeters (2 inches) wide. The smallest egg-eater examined (right) was about 21 centimeters long. It could fit a cylinder 1.4 centimeters (0.5 inch) wide in its mouth.B.C. Jayne/Journal of Zoology 2023

Jayne works at the University of Cincinnati in Ohio. He inspected 15 egg-eaters. They ranged from some 20 to roughly 90 centimeters (about 8 inches to about 3 feet) in length. After euthanizing the animals, Jayne slid a series of 3-D printed cylinders into the snakes’ open mouths. Each cylinder was wider than the last. This allowed Jayne to determine the biggest thing each snake could fit in its mouth.

The biggest of these snakes had a head roughly 1 centimeter (0.4 inch) wide. But it could swallow a cylinder a whopping 5 centimeters (2 inches) across. Data from past studies show that a petite Burmese python of the same length could gobble up prey just 4.4 centimeters wide. The western diamondback rattlesnake rivaled the python’s gift for gulp. No other snake species that’s been studied came close.

How does the Gans’ egg-eater open so wide? The soft tissue between the tips of its left and right lower jaws at the “chin” is super-stretchy. “In Burmese pythons, about 40 percent of [mouth] area is a result of the stretch of the skin between the lower jaws,” Jayne says. “But these guys edge out the pythons.” About 50 percent of the Gans’ egg-eater’s maximum mouth size is due to soft-tissue stretch.

Open wide! This Gans’ egg-eater snake swallows a bird egg whole and uses its spine to crack the egg open. After ingesting the egg’s contents, the snake spits out the shattered shell.

Why did this small snake evolve such an impressive ability to open wide? Compared with foods that other snakes eat, such as rodents, “an egg is super short,” Jayne says. “You have a limited ability to have a very long egg. But if you get your mouth wider,” he explains, “then you can consume these larger eggs.”

So far, maximum mouth size has been measured for only 13 of more than 3,500 known snake species. But Jayne plans to keep investigating the mouth sizes for a wider variety of them. For instance, he’s curious about snakes that eat fish. Those data could reveal whether Gans’ egg-eaters truly have the biggest gulp for their gullet.

Maria Temming is the Assistant Managing Editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

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