Snakes’ Surprisingly Common Cannibalistic Behavior

Cannibalism, often viewed with revulsion, is a surprisingly common and strategically beneficial behavior in snakes, according to recent research. A comprehensive review of existing literature reveals that snakes have evolved to eat one another independently at least 11 times throughout their evolutionary history, often as a response to environmental stressors like food scarcity.

The Prevalence of Snake Cannibalism

Researchers, led by Bruna Falcão, a graduate student at the University of São Paulo, compiled 503 documented cases of cannibalism across 207 snake species. This extensive review, published in November 2025 in the journal Biological Reviews, demonstrates that cannibalism is not a rare anomaly but a widespread and ecologically relevant behavior.

Why Do Snakes Eat Each Other?

While the idea of cannibalism may seem disturbing to humans, for snakes, it appears to be a strategic adaptation. “For us humans, we don’t think of cannibalism as something common – it’s something weird and disgusting,” Falcão explained. “But for snakes, it’s quality for them; it’s good for their ecological fitness. … It’s strategic.”

Scientists are revisiting previous assumptions that considered cannibalism maladaptive, now investigating the evolutionary advantages it offers, particularly when resources are limited. Cannibalism can serve as a form of population control or an opportunistic predation choice.

Which Snake Families are Most Involved?

The study identified that cannibalism was most prevalent in three snake families: Colubridae, Viperidae, and Elapidae.

• Colubridae (29% of reports): This is the largest snake family, and the researchers suggest that cannibalism in this group is often linked to stressors like a lack of alternative food sources.
• Viperidae (21% of reports): Many of these cases occurred in captivity, suggesting that confinement and limited food availability may contribute to cannibalistic behavior.
• Elapidae (19% of reports): This family includes cobras, which are already known to prey on other snakes in the wild.

Diet and Jaw Structure Play a Role

Almost half of the snake species exhibiting cannibalistic behavior have generalist diets, suggesting that dietary flexibility may contribute to this behavior when necessary. Yet, a key factor is jaw structure – snakes must have jaws capable of opening wide enough to consume another snake. There were no reports of cannibalism in species lacking this ability.

Evolutionary History and Future Research

The researchers concluded that cannibalistic behavior evolved independently at least 11 times throughout the snake evolutionary tree. While most reports of cannibalism in snakes are anecdotal, this study provides a valuable overview of the phenomenon. Falcão notes that the review likely doesn’t encompass all instances of cannibalism, as many reports are found in older, less accessible books and archives, leaving room for further discovery.

The adaptability of snakes, found on all continents except Antarctica and thriving in diverse ecological niches, may explain the repeated evolution of this behavior. Cannibalism appears to be a reflection of their ability to opportunistically adapt to their circumstances.