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In Part 1, we discussed the different methods that snakes
use to find their prey. We also learned about the snake strike. Today, we'll
learn what happens after the strike.
A Deadly Bite and a
Tight Squeeze
Once a snake grabs hold of its prey, a few things can happen.
Venomous snakes begin injecting their victims with venom as they recoil from
the strike. Most keep their prey in their mouths, but some release their victims
and wait for them to die.
There are two basic types of toxins within snake venom:
neurotoxins and hemotoxins. Neurotoxins attack nerve cells. Different
neurotoxins affect nerve cells in different ways, but all lead to muscle
paralysis. Taipoxin, for example, causes the paralysis of respiratory muscles.
The victim dies of asphyxiation.
 Hemotoxins destroy blood cells, prevent blood from clotting,
and cause organ degeneration and tissue damage. Because hemotoxins destroy both
tissue and organs, a snake's prey isn't just killed. It's made easier to
digest.
Snakes can have one or both toxins in their venom. The
fangs, which are used to administer the venom, can be either hollow or grooved.
Some snakes are rear-fanged and others are front-fanged.
Rear-fanged snakes have grooves on the back on their fangs.
When a snake bites, its venom sacks contract. This allows the venom to flow
down the grooves of the fangs and into the bite wounds. By contrast, front-fanged
snakes have hollow fangs that act like hypodermic needles. Venom is injected
directly into the animal.
Most front-fanged snakes inject venom directly downward. But
some front-fanged snakes have injection openings that point forward. These
snakes, commonly known as spitting cobras, can eject their venom as a defensive
maneuver. Spitting cobras always aim for the eyes of the creature that
threatens them and are very accurate - even from a few meters away. If
immediately rinsed from the eyes, this venom causes temporary blindness.
Otherwise, blindness becomes permanent.
Constricting snakes coil tightly around their prey. Despite
what many people think, constrictors don't crush their prey. Nor do they break
any bones. In the past, it was believed that these snakes would coil so tightly
that the prey item could not expand its ribcage to inhale, leading to death
from asphyxia. It's since been observed, however, that many prey items die in a
shorter time than would be possible through asphyxia.
It has been suggested, too, that the increased pressure
within the body due to constriction is too much for a victim's heart to handle.
This results in immediate cardiac arrest in the prey item. Although this theory
has not been confirmed, ongoing research has presented data that suggests it is
possible.
One BIG Gulp
Once a prey item is killed, the snake begins to swallow it. Thanks
to an extraordinarily flexible skull, liberated mandibles, and very stretchy
skin, snakes are able to swallow prey that is much larger in diameter the snake
itself.
Snakes use their liberated mandibles and back-pointed teeth
to "walk" themselves over their prey. Once the prey item is past the snake's
teeth, the snake uses its muscles to push the food down to its stomach.
So how to snakes breathe while they eat? A snake's trachea,
or windpipe, opens at the bottom of its mouth. Snakes have the ability to
extend the windpipe, moving the opening further forward. This allows a snake to
continue breathing while it swallows food.
To see a video of a snake eating a mouse, click here.
The digestive juices of a snake are strong enough to break
down the nails, claws, and bones of its prey. But that doesn't mean that snakes
eat every part of their victims.
Egg-eating snakes swallow eggs whole, but do not eat the
eggshell. As the egg travels down the throat, inward-pointing bony spines
protruding from their vertebrae make slits in the shell. The snake squeezes out
the contents of the egg and then regurgitates the shell.
Three Meals a…Year?
 As I mentioned at the very beginning of my blog series,
reptiles are extremely efficient creatures. On average, a reptile uses about 3%
of the energy that a similarly-sized mammal uses each day. Because of this,
snakes do not need to eat as much food on a daily basis. Coupled with the fact
that snakes can eat food much larger than themselves, snakes can survive for
many days after eating a meal.
For example, when my snakes were babies they ate one or two
baby mice every week. Now that my snakes are a few years old, they eat a few
juvenile mice every two weeks. When they are adults they will eat 2-4 adult
mice every two weeks. The larger boas and pythons I used to take care of would
eat one or two large rats or rabbits each month.
Large snakes that are capable of eating small deer may go
for several months without ever feeling hungry!
What's Next?
My next entry will be about the snake life cycle. I
will discuss growing, development, and shedding. See you then!
Picture Sources:
animalpicturesarchive.com
freerepublic.com
Last Blog Entry
Snakes: Feeding Time! (Part 1)
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