Snakes flick their tongues to detect the chemical signals given off by nearby prey. This enables the snake to identify the exact location of their next meal. Depending on the species, they will then use capture/kill techniques that focus on either constriction or envenomation.
Most snakes are ambush predators, lying in wait to catch their prey as it moves by. Snakes depend less on sight and sound than they do on detecting vibrations and heat to find the location of their prey. Gliding snakes leap from tree to tree to catch their prey, while tree snakes will come down to the ground to hunt. Some snakes constrict their prey to immobilize them, while others will use venom.
You’ll notice a considerable variation in approaches between species based on the type of prey that’s found in the snake’s locality. Let’s explore the methods snakes use to detect, hunt, capture, and kill their prey.
How Snakes Hunt Their Prey
Snakes are extremely effective hunters. Let’s start by looking at the more general hunting patterns used by snakes before looking more closely at the different senses and skills that individual species use to their advantage.
Ambush Predators
The vast majority of snakes do not chase after their prey. Instead, they prefer to lie in wait for their prey to come close, depending on camouflage to keep themselves hidden while they wait. When their prey is within reach, the snake then attacks quickly and decisively. These snakes, including rattlesnakes and pythons, are ambush predators.
As frightening as these snakes may seem, especially if they are venomous like the rattlesnake, ambush predators are very cautious. Ambush predator snakes will not stick around for very long if their cover has been blown.
Researchers at Cornell University observed the behavior of timber rattlesnakes, which are known to hunt rodents by waiting near the rodents’ foraging sites for long periods of time. If the prey animal noticed the snake, the rodent would make a behavioral display to alert other animals nearby to the snake’s presence.
Interestingly, the snake also seemed to take the rodent’s display as a cue. The rattlesnake would immediately leave its ambush location and find a new foraging site far away to wait in with new, unaware prey.
Chase After Prey
Snakes aren’t usually fast-moving animals, but there are exceptions. Some types of snakes chase their prey at relatively high speeds. Examples of snakes that do chase after their prey include:
- Eastern racers. These colubrids can chase after prey at about 4 mph, which is the pace of a brisk walk.
- Galapagos racer snakes. Nobody has measured how fast they go, but they’re fast enough to catch iguanas, so they’re swift movers.
- Black mamba. They can reach speeds of 12mph+. That’s about as fast as an average human can sprint.
Pack Hunters
There are rare instances where snakes coordinate their hunting efforts with other snakes, working together to catch their prey.
Researchers from the University of Tennessee observed Cuban boas, snakes which mainly hunt bats. Cuban boas hang upside down from the ceiling of the entrance to the cave, catching the bats as they come out of the cave. The researchers noticed that the Cuban boas which hunted alone, hanging far away from other snakes, were much less likely to catch a bat and often had to go home without a meal.
The most successful snakes were the ones that positioned themselves near other snakes. Together, they formed a kind of fence across the cave, more effectively blocking the bats’ pathway out. These snakes did not appear to compete with each other over the bats, and all left in the end having eaten.
Senses That Snakes Use To Hunt
Snakes of all types have a wide range of sensory tools that they use to find their prey. Let’s explore some of these senses in greater depth.
Hearing Vibrations
Snakes do not “hear” in the same way that a human does. A lot of them do not even take in sound waves from the air at all. This is because snakes lack an outer ear with which to gather these airborne vibrations. However, snakes do still have all the necessary bones and workings of an inner ear, which can pick up vibrations from elsewhere.
When a prey animal moves across the ground, this causes a slight vibration that a snake can detect. These vibrations are picked up by the snake’s jawbone and translated into a sort of “hearing.” Snakes can use the vibration they feel in their jaws to pinpoint the location of their prey.
Seeing Heat
Many species of snakes hunt at night, when their surroundings are much cooler. This means that there is a distinct difference between the cooler ground and trees and the warmer body of live prey. When a snake can’t depend on sight, it can often depend on heat.
Pit vipers have the ability to hunt prey by their thermal signatures. These snakes have heat pits on their heads which are sensitive to the slightest changes in heat in their environments. This allows the snake to “see” its prey even when there is no sunlight to see by. Other snakes that have similar heat pits to the pit viper are pythons and boas.
How Do Snakes Kill Their Prey?
There are many kinds of snakes, and each has a strategy for hunting, catching, and killing prey.
Water Snakes
Water snakes are usually non-venomous and range through the southern and eastern United States. They spend their time swimming and basking in calm, shallow waters. They are known to be aggressive when approached.
These snakes feed on smaller animals near or in their watery homes. This can include amphibians such as salamanders, toads, and frogs, but the snakes largely prefer slow-moving fish.
Water snakes sometimes behave as ambush predators. They wait in shallow waters with their mouths wide open, and when a fish passes by, they snap their jaws down around it. These snakes are also foragers. They will crawl along the bottom of their river or lake, searching under rocks and branches for prey which is hiding there and eating it quickly before it can escape.
A few species of water snake have proteins in their saliva which function like venom. While they do not pose any danger to humans, this venom is an anti-coagulant which can hurt smaller animals. Anti-coagulant makes wounds bleed more than they would otherwise. If a fish is bitten by one of these water snakes but manages to escape, then the snake can follow the trail of blood to catch its prey again.
Snakes cannot chew their food. Some water snakes solve this problem by only choosing bite-sized food and swallowing it whole. However, one species of water snake in Malaysia has been observed ripping up larger crabs into more digestible bite-sized pieces.
Gliding Snakes
There are 5 species of gliding snakes, also known as “flying snakes.” They live in tree-covered areas of South and Southeast Asia, including forests and jungles. These snakes fling themselves off of high branches, flattening out their body to help themselves glide through the air. They make S-like serpentine movements to control their direction on the air currents. They are able to travel more than one hundred meters in a single glide.
While many snakes hunt at night, gliding snakes usually hunt during the day. The prey of choice for these carnivores include birds, frogs, rodents, lizards, and bats. The snake will climb to the top of one tree to hunt. When it spots its prey on the lower level of another tree, it will leap out to glide down and catch it.
Gliding snakes do have venom, but their fangs are small and fixed at the rear of their mouth. The snake needs to quickly get its prey to the back of its mouth in order to make use of the venom. This means that gliding snakes focus on smaller prey which they can get their mouths around more easily. Once bitten and injected with venom, the prey becomes more lethargic and easier to swallow.
Tree Snakes
Gliding snakes never come down to the ground to hunt, staying high above to avoid predators of their own. Tree snakes, on the other hand, will come down to the ground to hunt their prey. These snakes include the green tree snakes of northern and eastern Australia.
Tree snakes are fast climbers and active hunters. They eat a wide range of foods, including geckos, frogs, lizards, skinks, small mammals, water skinks, reptile eggs, and even fish or tadpoles if they come close enough to the shore. Tree snakes use their sense of smell to find their prey, using their heads to poke through leaves and dig through loose soil to find hidden meals.
These snakes are not venomous and usually do not depend on biting to subdue their prey. Rather, they swallow their prey whole. These snakes which eat their prey alive depend on speed to snatch up and swallow their prey. This also limits the size of prey that these snakes can eat. Tree snakes cannot digest an animal which is much wider than its own body.
Constrictors
The image of a snake wrapping its coils around a smaller animal quickly comes to mind. This behavior is called constricting. Constrictors include anacondas, ball pythons, and boa constrictors.
Copeia, a journal published by the American Society of Ichthyologists and Herpetologists, identifies three different methods within the general strategy of constricting. Some snakes coil around its prey with their underside against the prey animal. Some coil with their dorsal side against the prey animal. A third group makes irregular, overlapping coils with no consistent surface held against the prey animal.
Constrictors perform this behavior instinctually. Even if the prey is already dead, the snake will constrict its prey. The snake will twist itself around the prey, moving with a live prey’s movement to help itself wrap more coils around it.
It has been long believed that constrictors suffocate their prey, causing a slow, agonizing death. However, this is not the case. A boa constrictor wrapped around a rat does not cut off the rat’s ability to breathe. Instead, it blocks the flow of blood to the rat’s heart, causing the rat to have a heart attack. This is a quick method of killing, not the long torture of suffocation.
Venomous Snakes
Another image that may quickly come to mind when thinking of how snakes hunt is the snakes with venomous fangs. Not all snakes have venom, and the vast majority of venomous snakes are not dangerous to humans. Venom is a tool for snakes to help them immobilize their prey.
A snake that hunts a small, quick-moving animal needs a way to keep that animal from escaping. Constricting works well against larger animals but not smaller ones, which can wiggle free. Venomous snakes lie in wait until their prey comes by, and quickly bite the prey once, injecting the venom. This bite alone is not enough to kill, but the venom does the rest of the work to slow the prey down.
There are several different types of venom. One is a neurotoxic venom, which quickly causes the prey to become paralyzed, allowing the snake to catch up to its now-dead prey. Another type of venom is hemotoxic. Hemotoxic venom does not kill its prey immediately, but it causes a significant amount of internal bleeding which similarly immobilizes the snake’s prey. After injecting its venom, the snake need only wait a short time before its prey is vulnerable enough to eat.
