Snakes in popular culture are often treated as voracious and alien creatures, and there’s some degree of truth to that. The ability for snakes to unhinge their jaws and swallow prey of seemingly impossible sizes whole is incredible, and that’s doubly true when speaking of an enormous snake like an anaconda. But what may seem horrifying to us is a sign of evolutionary success.
Natural selection caused the snake to lose the four legs its ancestors have, but serpent species have now come to represent a third of the total number of reptile species. On the surface, the snake takes several complex biological processes and reduces them to their most basic parts for the sake of accommodating its primitive body shape. But that’s also forced snakes to adopt some truly creative — and often ghastly — characteristics to help them perform tasks that creatures like humans and chimps take for granted.
Due to some of these unique alterations, snakes can go a long time without needing a meal. But the whys and the hows are the important part of the answer. This is how some snakes have developed the ability to go for long periods without eating and how circumstances led to them becoming this way.
How Snakes Consume Their Prey
The open and hissing jaw of a snake might be terrifying up close, but it’s also a reminder that we’re lucky to be able to chew. All snakes are ambush predators, but they’ve developed three primary methods for consuming prey, each of varying effectiveness depending on the size, nature, and environment of a species.
Venom is perhaps the most effective. The needle-like fangs of snakes may not be great for ripping and tearing at an animal’s body, but they’re effectively built like hypodermic needles. Once the venom does it work — by either killing or paralyzing prey — the snake can get to work swallowing it. In some cases — such as with pit vipers like rattlesnakes — the venom can even begin the process of liquefying a prey animal’s insides to make them easier to digest. But only about one in five snake species is venomous.
Constrictor species are more common, as they use various methods of crushing their prey to incapacitate them before swallowing them. Others — like the garter snake — are simple effective predators that can reach out and swallow prey whole. For constrictors and venomous snakes, the real chore comes from actually swallowing their prey. Unable to rip or cut the flesh, these snakes have to open their jaws as wide as they can and slowly wiggle their lower jaws underneath the prey animal like lining up a forklift. A snake’s upper and lower jaw don’t detach from one another, but it can open up to four times the width of a snake’s body. Their skin is similarly designed for flexibility, and to form around the food item.
How Snakes Expend Their Energy
Wrapping your head around how these legless reptiles can go so long without food requires an understanding of how and why different types of animals require dramatically different amounts of energy. While the organisms that cover this planet take incredibly diverse forms, the process of natural selection that underlies everything is driven by the simple arithmetic of energy expended and energy consumed. As warm-blooded animals, humans and all other mammals can maintain their body temperature internally. While this allows mammals to be more active than their reptilian counterparts, this active metabolism is also costly in terms of energy. The cheetah is the world’s fastest land mammal, but properly maintaining that body means eating over six pounds of meat a day.
Reptiles can afford to be more energy efficient because they use an external power source. Natural heat and light get them active and moving, and snakes can work at optimum effectiveness between 80 and 90 degrees Fahrenheit. Their lower metabolic rate means that they have to consume less food in the first place, and the average reptile requires only 20 to 25% of the nutrient intake of a mammal. It’s an effective way to succeed because it allows them to succeed even when opportunities might not be sustainable for more lethal but also more energy-dependent mammal predators. It also allows them to effectively live through cold weather without having to absorb the cost of maintaining their body heat or developing specialized behavior like hibernation.
How Snakes Digest Their Prey
Being able to disable their prey with a single venomous bite and then swallow them whole often allows these ambush predators to both hunt and feed with very little energy expenditure — but digesting their meal is a very costly process. The Burmese python is an extreme but representative example. Once a fresh meal is carried into the esophagus and begins the chemical process of being broken down inside the snake’s stomach, this serpent’s body begins to mutate wildly. Their metabolism will accelerate up to 44 times its original rate, and their organs can grow up to two times in size to maximize the efficiency of the digestion process. This isn’t the norm, but it’s impressive when you consider that most snake species will typically eat a quarter of their body weight in a single sitting. Pythons are especially voracious eaters, and some pythons have been known to eat up to 95% of their body weight.
Human beings may need three square meals a day, but a snake can simply gorge once and then take a long nap while digesting it. The actual digestion process can vary depending on the size of the snake, the surrounding temperature, the size of the meal, or several other conditions. Shorter meals can take three days, but it could take a massive snake, like an anaconda, weeks to fully digest a larger meal such as a deer.
There are dangers involved with longer and more difficult digestion processes. Larger game is more likely to have horns, fangs, or claws that can pierce an internal organ and kill the snake. They need to be exposed to heat to properly digest, but they’re also vulnerable targets as long as they’re engorged with their meal. And while the digestive acids being used are potent, a serpent’s organs are in a race against their prey. If it can’t dissolve the prey faster than the corpse can decompose, the snake’s meal could poison it, grow inside its stomach, or trigger the explosion of gases. It can be a costly risk, but a big meal dramatically increases the amount of time that a snake can go without eating.
The Average Snake’s Dietary Schedule
In terms of how often and how much food the average snake needs, it can vary tremendously between different species. Researchers have identified both frequent and infrequent feeders, with the latter exhibiting the behavior of ball pythons demonstrated for growing their organs to assist with digestion. Baby snakes and frequent feeders might eat about twice a week, while infrequent feeders may comfortably go without eating for a couple of weeks at a time. In extreme cases, it might be weeks before the last meal is even digested.
As reptiles, snakes are also capable of a state called brumation which allows them to sink into a deep torpor during colder months. It can be a critical method for survival when prey can be scarce and hard to track — and with a lack of sunlight and heat, most snakes are ill-equipped to hunt anyway. Corn snakes are known to go two to three months without food during brumation, but many species will take periodic breaks during longer brumation periods to hunt for new food.
How Long Snakes Can Go Without Food
A baby snake will begin to seriously starve after roughly a week without food — and once that baby grows into an adult, members of most snake species can comfortably get by for at least two to three weeks. But the time it takes for a snake to starve can depend significantly on the species. Smaller snakes tend to feed more often than larger ones, but species like the ball python can go for as long as two years without needing a meal. Without an internal metabolism to manage, the energy cost of doing nothing is a lot lower than it would be for an equivalent mammal.
That said, science is just beginning to uncover the full survival capabilities of snakes. A study that looked at the tactics snakes employ when they might starve took various snake species and observed their behaviors when they were fed nothing for six months. In addition to their naturally low energy needs, three separate snake species demonstrated the capacity to further lower their metabolism by as much as an additional 70%. It’s a fascinating but still uncertain look into how these creatures operate and how they might conceivably be able to survive without food for even longer periods than we think possible.