Cobra Cannibalism: Snakes Eat Each Other in Bizarre Study
"Instead of capturing two potential study animals, we found one well-fed study animal."
There’s no easy way to say this: Lots of cobras are cannibals. Fortunately, they’re not alone in this taboo behavior. A lot of animals engage in cannibalism. Chimps eat other members of their own species, and even humans have been known to indulge. When it comes to snakes, though, the reasons behind eating each other are a little bizarre.
In a paper published Monday in the journal Ecology, a team of researchers in South Africa outlined their observations and some potential hypotheses for why a surprising number of cobra species in the region feast on their bröthers. While ophiophagy (eating members of other snake species) has long been observed among snakes, researchers suspected that outright cannibalism (eating members of the same species) wasn’t intentional. Rather, it was thought to be opportunistic, like when a snake was hungry and just happened to see another long boy sitting within eating distance.
But after performing field observations in the Kalahari Desert, the paper’s authors had a new hypothesis: It looks like cobras in South Africa probably aren’t just eating each other by chance.
Long story short — get it? — out of the six cobra species they studied, they observed five engaging in cannibalism. The paper’s authors, led by Bryan Maritz, Ph.D., a senior lecturer in biodiversity and conservation biology at the University of the Western Cape in South Africa, also found that snakes make up 13 to 43 percent of wild cobras’ diets.
In the paper, the researchers describe a field excursion in the Kalahari Desert in January 2018, during which they were trying to investigate resource competition between the cape cobra (Naja nivea) and the boomslang (Dispholidus typus). They got a lot more than they bargained for, though, when a nearby tour guide announced over the radio that two large yellow snakes were fighting. They rushed over, hoping to see two male cape cobras in ritual combat. By the time they reached the scene, it was too late.
“Instead of capturing two potential study animals, we found one well-fed study animal, now known as NN011, or more casually, Hannibal,” wrote the study’s authors, who are clearly very amused with themselves.
Perhaps just as fascinating as the mere fact of snake cannibalism, though, is why they do it. While we obviously can’t get into the cobra brain to understand the motivation behind cannibalism, the researchers propose that it could have something to do with sexual competition. After all, every individual involved in cannibalism was a male, whether it was the eater or the eaten.
“This male bias in our observations raises the question of whether cannibalism evolved from a male-male combat behavioral precursor, especially given that male-male combat in cobras is known to include biting,” they wrote. But be that as it may, it’s also entirely possible that snakes eat each other because it’s easy.
Think about it: What fits inside a snake better than another snake?
“Their gross morphology and gape-limitation” — that is, how wide they can open their mouths — “mean that snakes and other elongate prey offer the greatest value in terms of prey mass relative to cross-sectional size,” wrote the researchers. “This means that snakes (including conspecifics) represent relatively enormous meals with important energy balance and fitness implications for snakes that are consuming them.”
More research will be necessary to confirm these hypotheses, but for now, it’s safe to say if you’re missing a pet cobra, maybe you should look in the belly of your other pet cobra.