Snake Myths and Facts - Reptiles by fjzhangxiaoquan


									Snake Myths and Facts
The facts and truth behind the eight most common myths about snakes.

By Phil Purser

5) Rattlesnakes Always Rattle a Warning Before They Strike.
Never believe this myth. It’s simply not true. Rattlesnakes evolved rattles to announce their presence in a landscape filled
with large, hoofed herbivores during the Pliocene period in North America (Ernst 4). Made of old skin links retained after
each shed, this rattle, especially one from an older rattlesnake, can produce a surprisingly loud, crisp buzz that can be heard
many yards away. A bison or other large mammal moving through thick vegetation quickly learned to heed the loud buzzing
warning of the rattlesnake’s rattle. This survival tactic benefited both the rattlesnake and the bison. The rattlesnake was not
stepped on or crushed, and the bison did not sustain a painful, if not crippling, snakebite.

But wait. If the rattle on a rattlesnake’s tail is designed specifically to warn nearby animals of the snake’s presence, then
why won’t one rattle before striking a human? The answer is simply one of mathematics. All snakes “hear” approaching
animals by detecting vibrations through the ground and substrate, so a rattlesnake rattles when it hears an approaching
animal. They can easily detect and warn approaching bison, which weigh 1,000 to 2,000 pounds. They are less likely to feel
the approaching footfalls of a 170-pound person and even less likely to detect the sneaker-dampened approach of a
75-pound child. Thus, humans have greater chances of surprising rattlesnakes and being bitten. If a rattler detects an
intruder too late, and this intruder is threateningly close, a surprised snake is more likely to strike in self-defense than buzz
its tail.

6) Snakes Cannot Strike Underwater.
Anyone even remotely familiar with the feeding habits of aquatic and semiaquatic snake species found throughout the world
can immediately detect the falsity of this myth. How could a snake, such as a red-bellied water snake (Nerodia erythrogaster
erythrogaster), which eats a diet consisting of fish, tadpoles and aquatic frogs, possibly subdue its prey without the ability to
strike underwater? Some, if not all, members of other genera, including Agkistrodon, Thamnophis, Bitis and Rhabdophis,
eagerly capture fish and fully submerged reptiles and amphibians.

To anyone still not convinced of the bogus nature of this myth, I submit the sea snakes of the genera Laticauda, Aipysurus,
Astrotia, Emydocephalus, Hydrophis, Lapemis, Acalyptophis and Pelamis. Members of these genera spend most of their
lives under the ocean’s waves and dine on fish, freshly molted crabs and other marine fare. Pardon the puns, but if
someone breaks the surface of this myth and dives deeper, it is pretty easy to blow it out of the water.

7) Some Snakes Can Sting With Their Tails.
This myth is a particular favorite of mine, and it originates from two snake species found throughout the southern United
States. One is the copperhead. When born, young copperheads are tan and copper over most of their bodies, but their tail
tips are vibrant yellow to chartreuse-green. Although some rural people say this highly visible coloration is a key sign of the
tail’s venomous “sting,” the tail’s actual purpose is to attract prey. As the baby copperhead lies motionless and superbly
camouflaged among leaf litter near the edge of a forest stream, it raises the tip of its tail out of the leaves and wriggles and
twitches it about. This lure closely resembles a struggling worm or caterpillar. When a hungry frog or toad duped by the
wriggling tail moves in for the kill, the young copperhead strikes, making a meal of the unfortunate amphibian.

The second species deeply contributing to the stinging snake myth is the eastern mud snake (Farancia abacura abacura).
Found throughout the swamps and wetlands of the southeast coast, this snake has a sharply pointed tail. In the natural
history tome Living Snakes of the World in Color, John M. Mehrtens describes the mud snake this way: “The tip of the tail
terminates in a sharp, conical scale ... (that) aids the snake in manipulating its slippery prey of salamanders and fish into an
alignment allowing for ease of swallowing. ... It is also used as a somewhat feeble deterrent against ... predators in being
repeatedly pressed against the skin of the aggressor” (Mehrtens 186).

Besides pressing its sharp tail against the skin of its attackers, this snake adopts a unique defensive posture when flight into
water or soft mud is not an option. It holds its tail aloft from its body and curls the rigid tip into an aggressive spearlike
implement. This tail-coiling posture is particularly prevalent in the western subspecies F. a. reinwardti, which is found in
eastern Texas north to southern Illinois. The mud snake’s posturing and skin-poking has earned the species the local
monikers “horn snake,” “stinging snake” and even “scorpion snake.” At the end of the day, however, it seems the stinging
snake myth is all bark and no bite.
8) Baby Venomous Snakes Are More Dangerous Than Adults.
This myth is roughly two-thirds nonsense and one-third truth. I believe this myth was born out of the human fascination with
irony. For some reason we like to think it’s the one we don’t see coming that always gets us. We like to root for the
underdog, and we simply like the notion of the tiny one being the deadly one.

But the fact of the matter is that baby venomous snakes are not more venomous than their parents. In fact, quite the
opposite is true in a great many snake species; adults have far more virulent venom than the young snakes. For example,
both adult and juvenile timber rattlesnakes (Crotalus horridus) have venom that is “strongly hemolytic,” which means it
causes the breakdown of red blood cells, in prey (Ernst 116). Yet venom studies in older adults demonstrate that the “activity
level of some venom enzymes tends to increase with the size and age of the snake” (Ernst 116). So an older timber
rattlesnake has venom more virulent than a younger one.

Similarly, an adult snake is capable of delivering a much larger venom dose than a smaller snake. Consider the eastern
diamondback rattlesnake (Crotalus adamanteus). Juveniles of the species typically deliver less than 70 milligrams of venom,
whereas a healthy adult specimen may deliver 492 to 666 milligrams of venom (Ernst 90). The known maximum is 848
milligrams in a single bite (Ernst 90). Roughly 100 milligrams of venom is considered a lethal dose for an adult human.

So if the venom toxicity of a young snake is not as potent as an adult, and the total venom yield of a juvenile is not nearly as
great as an adult’s, what part of this myth is one-third true? The answer lies in the venomous snake’s experience level.
Adults are veterans of life. They have successfully avoided or driven back predators and attackers, and they have full control
over all muscular functions. Adults recognize the need to conserve their precious venom. It takes time to produce it, and a
snake that empties its venom reserves in an attacker has nothing left to subdue prey. They have learned that a venomous
snake without venom doesn’t eat.

It’s a different story for neonate venomous snakes. They generally are not as in control of their muscular functions as are
adult snakes, and they are at their most vulnerable point in life. Defensive strikes are fast and thorough. When these snakes
bite, they typically bite hard, pumping the attacker full of every last bit of venom. If a young venomous snake’s bite were to
be more dangerous than an adult’s, this would be the only way.

I suppose there are far more myths about snakes than I can dispel in one article. Education is the key. Snakes are
interesting and unusual animals, so it only seems natural that people have attributed to them unique or even supernatural
properties and powers.

Sadly, too many of these untruths are passed down from one generation of reptile lovers to the next. I can only hope those
kids I saw at that Alabama reptile expo so long ago come to figure out that juvenile copperheads are not more virulent than
their adult counterparts. Because for every snake myth we bust, we get closer to allowing the truth behind these intriguing
animals to prevail.

Ernst, Carl H. 1992. Venomous Reptiles of North America. Smithsonian Institution Press, Washington, D.C.
Mehrtens, John M. 1987. Living Snakes of the World in Color. Sterling Press, New York, New York.

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