Wild snakes eat almost exclusively other animals, but exactly what ends up on the menu varies enormously across the more than 3,000 snake species worldwide. Small species living in leaf litter may eat nothing but ants and earthworms, while giant constrictors like anacondas can take down mammals as large as antelope. Most snakes fall somewhere in between, feeding on rodents, frogs, lizards, fish, birds, and eggs.
Common Prey by Snake Size
A snake’s size is the single biggest factor determining what it eats. Small snakes (under two feet or so) tend to target invertebrates like earthworms, slugs, snails, insects, and centipedes. Medium-sized snakes, which include most of the species people encounter in backyards and trails, feed heavily on rodents, frogs, toads, lizards, and bird eggs. Large constrictors like boas and pythons eat rabbits, opossums, deer, and other sizable mammals.
Baby snakes eat the same types of prey as adults but in miniature. A hatchling rattlesnake hunts tiny lizards and frogs rather than the rats its parents eat. As snakes grow, their prey shifts upward in size accordingly. The general rule is that a snake targets prey roughly the same width as its own body.
Specialists With Unusual Diets
While many snakes are generalists that eat whatever they can catch and swallow, some species have evolved remarkably narrow diets. African egg-eating snakes (the genus Dasypeltis) consume nothing but bird eggs. They swallow eggs far larger than their own heads, then use specialized bony projections on their vertebrae to crack the shell internally, squeeze out the contents, and regurgitate the crushed shell. They’re considered some of the cleanest feeders in the snake world.
King cobras earned their name because they eat other snakes, including venomous cobras and kraits. According to the Smithsonian’s National Zoo, king cobras mostly eat larger harmless species like rat snakes and pythons up to about ten feet long, but they’ll also consume small king cobras. Other snake-eating specialists include kingsnakes and the South American mussurana.
Some species have evolved to feed on prey most predators ignore entirely. Certain snakes specialize on slugs or snails, others eat only lizard eggs, and at least one species feeds exclusively on sleeping lizards. There are even snakes that target only elongated, legless prey like eels, other snakes, and legless lizards.
What Sea Snakes and Water Snakes Eat
Sea snakes, which spend their entire lives in the ocean, feed primarily on small, slow-moving fish that live near the sea floor. Studies of sea snakes in the Persian Gulf found their diet was dominated by gobies and mudskippers, with some species also eating eels and elongated fish. A few sea snake species occasionally eat fish eggs or marine invertebrates, but fish make up the vast majority of their diet.
Freshwater snakes like water snakes and cottonmouths eat frogs, tadpoles, crayfish, and small fish. Garter snakes, often found near streams and ponds, are generalists that eat earthworms, frogs, salamanders, and minnows depending on what’s available.
How Snakes Catch and Swallow Prey
Roughly 600 of the world’s 3,000-plus snake species are venomous, which works out to about one in five. Venomous snakes like vipers, cobras, and coral snakes strike and inject toxins that paralyze prey and begin breaking down tissue before the snake even starts swallowing. Constrictors like boas and pythons coil around their prey and squeeze until the animal’s heart stops. The remaining species, including many common garden snakes, simply grab prey and swallow it alive.
All snakes swallow their food whole. Their skulls are built for it. The left and right sides of a snake’s jaw operate independently, ratcheting forward over the prey in an alternating motion that walks the snake’s head over the animal. The lower jaw tips are not fused together like ours, giving snakes an enormous gape relative to their body size. This is how a snake can swallow a mouse, egg, or frog that looks far too large to fit.
How Snakes Digest Their Meals
Snake stomach acid sits at a pH of about 1.5 to 2.0, comparable to human stomach acid, but snakes take much longer to process a meal. A single feeding can take roughly a week to fully digest, depending on the size of the prey. During that time, the snake’s metabolism ramps up dramatically. Everything gets broken down: bones, fur, feathers, scales, and claws. The only things typically passed or regurgitated are indigestible items like eggshells (in the case of egg-eating snakes) or occasionally large clumps of hair.
Because digestion is so energy-intensive, snakes are vulnerable after eating. Many species seek shelter and remain inactive for days while processing a large meal.
How Often Wild Snakes Eat
Feeding frequency depends heavily on the species, its size, and how it hunts. Active foragers that cruise through their habitat searching for prey tend to eat more frequently, sometimes every few days, and have higher baseline metabolic rates. Ambush predators like pit vipers, which sit and wait for prey to wander past, eat less often but typically take larger meals relative to their body size. Their resting metabolism is lower, meaning they burn less energy between meals.
Small, active species like garter snakes may eat several times a week during warm months. Large pythons and boas can go weeks or even months between meals after consuming a sizable animal. In extreme cases, some large snakes have been documented fasting for close to a year when prey is scarce. Snakes in temperate climates also stop eating entirely during winter brumation, a reptile version of hibernation.
How Wild Snakes Stay Hydrated
Snakes get some water from their prey, but they also drink. Wild snakes hydrate from puddles, streams, dew, and rainwater collected on leaves or their own scales. Research shows that feeding increases thirst, so snakes tend to seek out water more actively after a meal. All snakes will readily drink fresh water when even slightly dehydrated, and aquatic species balance their hydration and electrolytes using the water sources in their environment.