Nature Bulletin No. 521-A March 16, 1974
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation
The story goes that, before Queen Cleopatra of ancient Egypt took her
life with the bite of an asp, she tested its deadliness on her slaves. Many
primitive peoples used the venom from snakes to poison their arrows. In
fact, until the 17th century, there was more exact knowledge concerning
poisons, especially snake venom, than of medicinal drugs. Their results
were more certain and immediate. Modern pharmacology, the study of
the action of drugs, grew out of this early lore about poisons.
Venomous snakes are native to every continent but are scarcer in
temperate zones than in tropical countries. Their venom aids in the
capture of small animals for food and helps defend them against large
animals and man. Of about 40,000 human deaths from snake bite in the
world each year, over half are among the crowded populations of India
where it is customary to go barefoot. Brazil formerly had 5,000 deaths
annually. In the United States, rough estimates from incomplete reports
indicate that several hundred people are bitten each year of which about
one in ten may die -- chiefly from rattlesnake bites in the southern and
southwestern states. In Illinois, there have been few, if any, deaths from
a wild native snake since records have been kept.
Poisonous snakes of the United States include the coral snakes,
cottonmouth moccasin, copperhead, and about 20 kinds of rattlesnakes.
The coral snakes, small relatives of the cobra, are found in small
numbers in our southeastern states. All of the others are "pit vipers, "
so-called because of a pit on each side of the head between the eye and
the nostril. Four of the pit vipers occur in Illinois, but are uncommon or
rare, the cottonmouth and the copperhead of the southern counties, the
timber rattler, and the little massasauga or swamp rattler. Cook County
has a few massasaugas in a couple of localities but there are probably
none of the menacing timber rattlers within 100 miles of Chicago.
Venom is a clear, pale yellow fluid secreted by glands connected with a
pair of hollow fangs hinged to the upper jaw. When the snake strikes,
the fangs are swung forward from the roof of the mouth and the poison
is injected into the punctures as if by hypodermic needles. Venom is a
complex of protein-like substances which, from different species, has
various effects. There are two main kinds -- the cobra type affects the
nervous system causing paralysis and the rattlesnake type destroys the
red blood cells.
The bite of a poisonous snake is a serious matter although not as
dangerous as many people suppose. The aid of a doctor should be
A few other animals with backbones are known to inject poisonous sub-
stances into punctures made by teeth or spines. There are several
examples among fish. In the sea, the sting ray can drive the toothed
spine on its tail into your flesh and produce excruciating pain. Others
like our little freshwater stone catfish have poisonous spines in their fins
that can cause an aching hand and arm.
Two venomous lizards are known in the New World, the Gila monster
of our southwestern deserts and its near relative, the Mexican
"escorpion." Among mammals, our tiny short-tailed shrew uses venom
for subduing prey.
In an entire lifetime here there is less danger from poisonous snakes
than in crossing one of our busy boulevards just once.
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Update: June 2012