Cannibalism, where one individual consumes another of its own species, is observed across diverse animal groups. This behavior often serves a purpose in survival. An intriguing question arises regarding whether snakes, known for their predatory prowess, also engage in such intraspecific consumption.
The Reality of Snake Cannibalism
Snakes engage in cannibalism, preying upon and consuming other snakes of their own species. While not a primary food source for most, intraspecific predation is documented in both wild and captive environments. This behavior is often driven by opportunistic circumstances. Its frequency varies among species and is influenced by environmental conditions.
True cannibalism, the consumption of a member of the same species, differs from ophiophagy, which is the general consumption of other snake species. Observations and scientific studies confirm that cannibalism, though sometimes rare, occurs among various snake populations.
Driving Factors for Cannibalism
Several factors can drive a snake to consume another individual of its own species. Food scarcity is a significant motivator, as snakes may resort to cannibalism when their typical prey becomes scarce due to environmental changes or habitat loss. This provides much-needed sustenance during lean periods, allowing the snake to avoid starvation. A 2013 study in South Africa documented instances of African Rock Pythons preying on smaller conspecifics during times of food shortage.
Territorial disputes also contribute to cannibalistic behavior, particularly among males competing for resources or mates. By eliminating a rival, the victorious snake reduces competition for territory and available prey, and potentially secures breeding opportunities. This aggressive interaction can sometimes culminate in one snake consuming the other, especially if there’s a significant size difference.
Mistaken identity can also lead to accidental cannibalism, especially when a snake encounters a conspecific that it perceives as a typical prey item. This is more likely to occur if the other snake is smaller or emits similar scent cues to its usual diet. For example, a snake undergoing shedding might have impaired vision, leading it to mistake its own tail for prey.
Stress, particularly in captive environments, is another documented factor. Overcrowding, inadequate habitat conditions, or a lack of environmental enrichment can induce stress, leading snakes to exhibit cannibalistic tendencies. A 2021 study in “Herpetological Review” highlighted cases of cannibalism among captive snakes attributed to such stressful conditions.
Notable Cannibalistic Species
Several snake species are recognized for their cannibalistic tendencies, either as a regular part of their diet or under specific circumstances. The King Cobra (Ophiophagus hannah), whose very name means “snake-eater,” is a prime example, primarily preying on other snakes, including venomous species. While often consuming other species, King Cobras have also been observed eating their own kind, particularly males, in contexts of territory or dominance.
Kingsnakes, native to North America, are well-known ophiophagous predators that readily consume other snakes, including venomous ones like rattlesnakes and copperheads. They are often immune to the venom of pit vipers, which facilitates this predatory behavior. Some species, like the Brazilian smooth snake, will consume their kin for survival, with other snakes making up 20-30% of their diet.
Documented cases of cannibalism include male Cape cobras eating rivals and male Montpellier snakes consuming females outside of mating season. Green anacondas are also known for cannibalism, with larger females occasionally consuming smaller males, possibly for post-breeding nutrition.
The Act of Consuming Another Snake
When a snake consumes another snake, the process involves remarkable anatomical adaptations that allow it to ingest prey often larger than its own head. Snakes do not dislocate their jaws, but rather possess a highly flexible jaw structure. The two lower jaw bones, or mandibles, are not fused at the front as in mammals, but are connected by an elastic ligament. This allows them to spread apart laterally, significantly increasing the width of the mouth opening, or gape.
The mandibles are also loosely connected to the skull at the back by bones like the quadrate and supratemporal, providing greater rotation and flexibility. During ingestion, the snake’s lower jaws move independently, allowing one side to advance and grip the prey while the other holds it in place. This “walking” motion of the head over the prey, sometimes referred to as a “pterygoid walk,” slowly pulls the meal into the throat.
Prey is often subdued first, either through constriction, where the snake wraps its coils tightly to cut off blood flow to the prey’s brain, or by venom injection. Once subdued, the snake swallows the prey headfirst, which streamlines the process and prevents limbs or coils from snagging. Backward-pointing teeth help maintain a grip and guide the prey deeper into the digestive tract. To prevent suffocation during this prolonged process, the snake can extend its glottis, a tube that opens to the trachea, outside its mouth, functioning like a snorkel to allow breathing.