Throughout history, snakes have evolved cannibalistic behaviors at least 11 times. Food scarcity is the main motivating factor.
Cannibalism may seem rare and aberrant, but a comprehensive new review suggests it is much more common in snakes than previously thought and has evolved repeatedly as an adaptive survival strategy.
In a published in November 2025 in the journal Biological Reviews, researchers analyzed more than 500 cases documented cannibalism in several species of snakes around the world. Their findings indicate that the behavior evolved independently at least 11 times during the evolutionary history of snakes, emerging in different lineages and regions.
Lead author Bruna Falcão, a postgraduate student at the University of São Paulo, said the team was surprised by the scope of the phenomenon. “The more we researched, more cases we found“, he said, noting that cannibalism appears to offer ecological advantages in certain contexts. Although humans often find cannibalism shocking, in snakes it can increase survival when resources are scarce or when opportunistic feeding is beneficial.
Researchers compiled 503 reports with 207 species of snakes, covering all continents where they occur and including wild and captive environments, says the . Cannibalism was especially prevalent in three big families of snakes: Colubridae, Viperidae from Elapidae.
The Colubridae family — the largest family of snakes — represented 29% of reports. As many colubrids are not specialized predators of other snakes, the authors suggest that cannibalism in this group may be driven mainly by environmental stress factors, such as food shortage.
The Viperidae family accounted for 21% of cases, the majority of which occurred in captivity, where confinement and limited food supply can increase stress-induced cannibalism. The Elapidae family represented 19% of reportsa less surprising discovery given that many elapids naturally feed on other snakes.
The study also found that almost half of cannibalistic snake species have generalist diets, suggesting that dietary flexibility may facilitate cannibalism when necessary.
Jaw morphology appears to play a fundamental role. No cases of cannibalism have been reported in species that could not open their jaws enough to consume another snake.
Snakes are among the most evolutionarily successful vertebrates, occupying numerous ecological niches on every continent except Antarctica. The repeated and independent emergence of cannibalism along its evolutionary tree may reflect this adaptability.
