predators, never taking vegetable food except by accident. They prey on small
mammals up to the size of rabbits, on birds, lizards, amphibians, occasionally
on fish and other snakes. Rattlers are heavy-bodied and not especially agile.
At top speed, which they can maintain only briefly, they crawl at a rate of
about three miles per hour, walking pace for a man. They have fairly good
vision but are shortsighted, not able to perceive movement much more than 15
feet away. There is some dispute on the matter but it is generally thought that
rattlers, which are earless, do not hear in the conventional sense. However,
they are sensitive to vibrations of the earth. Rattlers are good swimmers and
are not timid about entering the water.
A variety of
mammals will prey on rattlers, as will predatory birds, most especially the
red-tailed hawk. Wild turkeys, domestic turkeys and chickens will sometimes
kill rattlers. The king snake has a great and deserved reputation as a rattler
killer, but this is not an obsession or a matter of natural law and order. If a
king snake comes upon a smaller rattler it may kill and eat it. Cannibalism
among rattlers is rare but not unknown.
terms, the rattlers are a comparatively modern group of snakes, possessing a
variety of sophisticated and newfangled adaptations that their relatives lack.
For example, there are the pits that give this branch of the vipers its family
name. These appear on each side of the head between eye and nostril. They are
heat sensors and enable the snake, at distances up to a foot, to detect a
temperature difference of as little as one degree centigrade higher or lower
than that of the background. These sensors are particularly useful to the snake
as it hunts in dark tunnels.
The rattle is an
interlocking series of horny, multilobed segments attached to the tip of the
tail. When the segments are "rattled" against one another as a result
of an intentional muscular movement by the snake, they produce a distinctive
buzzing sound. The rattling apparatus is unique, and one wonders why it evolved
and what its function is. It has been suggested that rattlers rattle as a kind
of sporting gesture to give other creatures a head start before the snake comes
after them with the intent to poison or mesmerize. It has also been claimed
that the rattle is used in courtship, as a device for communication, or for
attracting curious and potential prey. These theories have now been discarded,
studies seeming to show that a snake rattles to bluff away creatures that might
do it harm. "Don't tread on me," is apparently the message and
function. The belief that rattlers will always rattle before striking is false.
Whether or not a rattler makes a noise depends upon the circumstances and, very
likely, the mood of the snake.
Perhaps the most
sophisticated of all the rattler adaptations, and certainly the one that has
earned its monster reputation, is the venom apparatus. The fangs work something
like a hinged hypodermic needle, being attached to the head bone in such a way
that they may be raised into a striking position or, when not in use, folded
back against the roof of the mouth. The fangs are hollow, encasing a venom
duct. They are an inch long and very sharp, but also very fragile and can be
broken or damaged easily. Fangs are replaced frequently, every two or three
weeks in some species. In the head of each rattler are at least half a dozen
sets of fangs in various stages of development. Periodically the functional
fangs are pushed out by the set growing in behind, much as the permanent teeth
of a child dislodge the baby teeth.
Venom is produced
and stored in glands located on either side of the snake's head. It is released
when muscles squeeze the gland, forcing the vanom down into the venom duct, and
into whatever the snake has struck.
When it comes to
lethal properties, real snakes can almost hold their own with mythical ones.
Unit for unit, and depending upon the species, reptile poison can be 40 times
as toxic as sodium cyanide, 30 times as toxic as typhoid endotoxin, seven times
as toxic as the Amanita mushroom, five times as toxic as the venom of a black
widow spider and twice as toxic as strychnine. Not only is it strong but it is
buffered by some 25 enzymes, biological catalysts that speed up its effect and
multiply problems arising from snakebite.
So complex is the
venom-enzyme cocktail of the rattler, it has thus far defied precise chemical
analysis. In consequence, venom is normally described in terms of the effects
it produces. These vary but in a broad way can be summarized as follows. In a
normal predatory situation, enzymes serve to predigest the snake's prey, as
meat tenderizer softens a tough steak. Injected into a man, the enzymes begin
to break down fibers and the cellular structure itself. They contribute to the
hemorrhaging that often accompanies snakebite and are also responsible for
"killing" the flesh in the area of the bite. Gangrene will sometimes be
a by-product of this, causing chronic problems long after the effects of the
venom have disappeared. The venom itself produces pain, swelling, nausea,
allergic shock, hemorrhaging, weakening of pulse, lowering of blood pressure,
increase in temperature, respiratory and circulatory difficulties and
unconsciousness. Generally, if death occurs, it is caused by neurotoxic effects
resulting in respiratory or cardiac failure or because hemorrhaging has so
riddled the vascular system that the heart can no longer pump blood through
Klauber was of the
opinion that the eastern diamondback was probably the most deadly rattler, not
because its venom was the strongest (other species are more toxic) but because
as the largest of the rattlers it could produce and inject more venom. With the
possible exception of the pygmy species, under the right conditions any
American rattler can inject enough venom to kill an adult.
All of which
Americans had been aware of before they knew what an enzyme was. With lots of
empiric evidence at hand demonstrating that snakebite was bad business, we have
tried during the past four centuries an enormous variety of remedies—animal,
vegetable and mineral—for snakebite. A list includes milk, eggs, tea, powdered
crocodile teeth, horned-toad blood, onions, garlic, tobacco, indigo (and about
a hundred other species of native plants), vinegar, turpentine, olive oil,
kerosene, iodine, potassium permanganate, salt, gunpowder, ammonia, mud, opium,
strychnine, ether, enemas, artificial respiration, song, dance, prayer and
amputation. A remedy well thought of and still used in many parts of the
country involves killing and splitting open a chicken or obtaining the heart or
liver of a cow or deer. The bloody meat is then pressed over the wound. It is
supposed to draw out the poison. It does not.