Snakes are predators with highly varied diets, consuming everything from insects and eggs to mammals and birds. Predation within the animal kingdom is common, yet the consumption of one’s own species, known as cannibalism or intraspecific predation, occupies a unique and often misunderstood place in biology. The question of whether this behavior extends to serpents has long been a subject of curiosity. Understanding the feeding ecology of these reptiles reveals specific circumstances that drive them to consume their own kind.
The Direct Answer: Defining Cannibalism in Snakes
Snakes do engage in cannibalism, which is the act of preying upon and consuming a member of the same species or morph. This behavior is a form of intraspecific predation. While this act is documented across many snake families, it is generally considered an opportunistic behavior rather than a routine dietary staple for most species.
This must be distinguished from the broader feeding habit known as ophiophagy, which is the specialized diet of eating any snake, including those of different species. The King Cobra (Ophiophagus hannah), for example, is a well-known ophiophage. Ophiophagy is a specialized strategy, while true cannibalism is a subset of this behavior and is widespread, documented in over 200 extant snake species across 15 families, including Colubrids, Vipers, and Elapids.
Motivations for Intraspecific Predation
One of the primary drivers for a snake to consume a conspecific is severe resource scarcity, which can lead to starvation. In a harsh environment with limited available prey, a smaller snake represents a substantial, high-value meal. This factor alone can override the natural tendency to avoid eating one’s own kind.
The size advantage between two individuals is also a strong predictor of cannibalism, as the predator snake must be significantly larger than its prey to ingest it successfully. The gross morphology and gape limitation of snakes mean that an elongated prey item, like another snake, offers the greatest mass relative to its cross-sectional size. This makes a smaller conspecific an energetically efficient meal, providing a large amount of nutrition for the effort.
In some cases, the behavior appears to stem from a misguided feeding response, treating a conspecific as just another available prey item. For aggressive feeders, a sudden movement or the scent of a prey item can trigger an indiscriminate strike. This is particularly observed in captivity, where stress or a strong hunger response can lead a snake to strike at its own body or a nearby cage mate.
Common Instances and Species Examples
Cannibalism is a well-documented phenomenon in specific groups of snakes, with certain species exhibiting the behavior more frequently.
Species Examples
The King Cobra and various species of African Cobras, such as the Cape Cobra (Naja nivea), are known for this behavior. Among males, this consumption is often linked to territory and dominance, with studies showing males frequently consuming smaller male rivals.
Certain constrictors, such as King Snakes (Lampropeltis genus), are inherently ophiophagous and will readily consume other snakes, including their own species. For these snakes, the act is a natural extension of their specialized diet, and they are even immune to the venom of many species they prey upon. The Mulga Snake (Pseudechis australis), Australia’s longest venomous snake, also includes conspecifics in its wide-ranging diet.
Filial Cannibalism
A specialized form of this behavior is filial cannibalism, where a parent consumes its own offspring. Female snakes, such as the Brown Rainbow Boa (Epicrates cenchria maurus), may consume unviable eggs or stillborn young after giving birth. This act is considered adaptive, as it allows the female to quickly recoup energy and nutrients lost during the reproductive period, assisting in recovery.
Biological Consequences of Snake Cannibalism
Consuming a member of the same species carries inherent biological risks that act as a deterrent under normal conditions. A significant consequence is the increased potential for parasite transfer. Since parasites are often highly adapted to a specific host species, eating a conspecific almost guarantees the ingestion of parasites that can successfully colonize the predator, potentially leading to a heavy parasitic load.
For venomous species, cannibalism presents the unusual risk of ingesting specialized toxins. However, many ophiophagous snakes have evolved mechanisms to resist the venom of their prey. Even for non-venomous snakes, the act can result in injuries if the victim fights back and inflicts damage before being swallowed. The presence of cannibalism within a population also exerts a strong evolutionary pressure, influencing male-male competition and acting as a mechanism for population density control.