Watch This Snake Violently Rip a Crab to Pieces with Its Mouth in Bizarre Hunting Behavior

The vast majority of snakes swallow their prey whole. However, the cat-eyed water snake (Gerarda prevostiana) from the mangroves of southeast Asia likes to do things differently, according to a new study published in the Biological Journal of the Linnean Society.

These animals violently rip their food to pieces, which is especially impressive given that they feast on spiky crabs.

A team of researchers from the University of Cincinnati (UC) found that the snakes wait until a crab has just moulted (crabs periodically shed their hard exoskeleton and replace it with a new one). New shells are much softer than usual, but they quickly harden.

"The snakes only have about a 20-minute window to eat the crab the way they really like them," Bruce Jayne, a UC biologist told the university magazine.

If the snake catches a crab during this window, it will be soft enough to rip apart. Night vision footage captured by Jayne shows a cat-eyed water snake biting a crab before pinning it down and crushing it with its body. It then proceeds to brutally tear off pieces from it, eating them one by one.

This method requires a lot of effort, but the rewards are significant—the cat-eyed water snake can eat prey up to four times bigger than what they would be capable of swallowing whole, giving them a survival advantage.

"These crabs are huge! The legs alone were nearly as big as the snake's gape," Jayne said.

A screenshot from an infra-red video taken in Singapore of a Gerarda prevostiana specimen ripping apart a crab. Bruce Jayne/University of Cincinnati

For their study, the Cincinnati team also examined the hunting behavior of two other closely related snakes—the white-bellied mangrove snake (Fordonia leucobalia) and Cantor's water snake (Cantoria violacea).

The former—which eats, small, hard-shelled crabs—also displays some unusual hunting tactics. Unlike most snakes that strike with an open mouth, Fordonia leucobalia pins its prey down with its chin, before coiling its body around it and swallowing it whole—sometimes while the crab is still alive. Fordonia's stomach is resistant to the hard-shelled crab's claws and spiky shell.

According to the researchers, the new study sheds light on a concept known as convergent evolution—the process by which different animals evolve similar adaptations.

"It really tests the idea of convergent evolution," co-author Harold Voris of the Field Museum of Natural History told the UC magazine "Do we see similar types of behaviors and morphologies and hunting tactics in different geographic areas? Or are there important differences that suggest it came about differently?"