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The Animal Science Blog is the place for conversation and discussion about scientific and technological topics related to pets, livestock, and other animals. See how cutting-edge advances help - or hinder - species around the world.

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Snakes: Feeding Time! (Part 1)

Posted May 05, 2010 12:01 AM by Vi Pham

How do snakes find food? When they find it, how do they catch it? And once they catch it, how do they eat? Let's find out!

On the Hunt

When snakes are hungry, their hunting behavior is triggered usually by the smell of prey. The speed at which a snake's tongue flicks in and out of its mouth increases dramatically. Because snakes "taste smells", this allows the snake to locate its prey more easily.

Some snakes will actively pursue a prey item. Other snakes employ the "sit-and-wait" method. Generally, a snake's hunting methods are determined by the abundance or scarcity of prey.

Mice and other, larger prey (rats, rabbits, deer, etc.) are seldom found in large numbers. So when a snake senses that food is nearby, the snake will go searching for it. Snakes will then pursue their prey until there is a good time to strike. This is when being extremely silent and having good camouflage come into play. Prey can't hear the footsteps of a hunter that has no feet!

Snakes that eat ants and other small insects often live very close to an ant colony or termite mound. When these snakes need to eat, they simply go to an area where there is a lot of insect traffic and catch the insects as they pass by. Bat-eating snakes tend to live in bat caves. They wait on a high ledge for when the bats fly in and out of the cave. The snakes then catch the bats in mid-flight.

Snakes native to desert areas are at a disadvantage. It is often difficult to find a large population of prey items. Plus, with so few plants or rocks to hide behind, it is very difficult for these snakes to stalk anything. Instead, many desert snakes bury themselves in the sand and lay still. When a prey item comes close enough, the snake strikes from under the sand - usually with great success.

Some snakes prefer immobile prey. Often, egg-eating snakes can find food easily. The sole concern of these snakes is to eat their meal before the prey's parents return to the nest. (picture provided by wikipedia.org)

Ready to Strike

With the exception of egg-eating and some insectivorous snakes, most snakes require the ability to quickly strike at and catch their food. Once the snake determines that it is close enough to the prey item, it curls into the "S" position and waits.

Snakes usually strike with the front 1/3 of their bodies. The more of their bodies they use, the less accurate the strike is likely to be. Snakes have to use a considerable amount of energy to propel themselves forward. Consequently, a full-body strike may reduce their focus, or just make it that much harder to maintain control of their bodies while in the air.

A snake's strike happens very quickly. Some snakes can strike more quickly than the reaction time of many animals, including humans. This is a considerable feat, since a person's reaction time can be as fast as a few hundredths of a second.

So what about animals that can react more quickly than a snake? Generally, a snake wouldn't bother trying to hunt prey that is too fast; however, scientists have found a snake that tricks its prey right into its jaws!

Like many other snakes, the tentacled snake (Erpeton tentaculatum) of Southeast Asia can strike in a few hundredths of a second. But the fish this snakes likes to eat have reaction times of just a few thousandths of a second. To overcome their significant disadvantage then, the tentacled snake doesn't strike the fish. Rather, it makes use of the fish's natural reflex.

Fish are very sensitive to changes in pressure. They have many sensory receptors on their sides that allow them to feel the movement of the water as them swim. When a fish feels a sudden increase in pressure on one side (indicating that something is coming towards the fish), it immediately turns away from the oncoming pressure and swims away from the object.

When the tentacled water snake is on the hunt, it positions itself in a "J" shape in the water; the snake's head sits opposite of its midsection. When fish swim close by, the snake remains still until one swims into the curve of the "J". As the fish swims between the snake's head and midsection, the snake very quickly jerks its middle in the direction of the fish. Because of the fish's natural reflex to swim away from the sudden movement, it immediately swims straight into the snake's ready jaws.

Here is a high speed video taken by biologist Kenneth Catania of the snake in action!

Next Time

Now that we've discussed how snakes find and catch their food, we'll learn how they subdue and eat it.

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Snakes: A Family Affair (Part 2)

Snakes: Clever And Deadly Behaviors

Snakes: Do The Locomotion (Part 1)

Snakes: Do The Locomotion (Part 2)

Snakes: A Look Inside

Snakes: Feeling Sounds And Tasting Smells

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