Genus/species: Agkistrodon piscivorus
Cottonmouths reach 30 to 48 inches (76 to 122 cm) in length,
occasionally up to 74 inches (1.8 m). The back is dark olive
or black, the belly is paler. On young animals the back is
marked by bands with dark borders and paler centers. This
pattern is usually lost in older individuals. The snout is
always pale, and there is usually a dark vertical line by
each nostril. The banding pattern in the young may be striking.
Cottonmouths are primarily active at night, but they bask
in the sun during the day. Because they spend much of their
time in water, and water draws away heat more quickly than
air, they must somehow maintain a high body temperature, particularly
for their digestive metabolism. This is accomplished partly
Cottonmouths have varying temperaments. They are usually
not aggressive and will not attack unless agitated. One of
their unique behaviors is their ability to "stand their
ground." When thoroughly aroused, a cottonmouth coils
its body and threatens the intruder with its mouth wide open
and its fangs exposed, showing the white lining of its mouth
(thus its common name, the cottonmouth).
The cottonmouth is a pit viper. It possesses a pair of heat-sensing
pits between their eyes and nostrils. The pit consists of
two cavities, an outer and an inner, which are separated
by a membrane. They are able to detect temperature differences
of as little as 1.8° F (1° C). higher or lower than
that of the background. They allow the snakes to strike
very accurately at the source of heat--often a bird or mammal
that is potential prey. The sensory apparatus is most efficient
at night when prey are much warmer than the surrounding
Distribution and Habitat:
Cottonmouths reside mainly in the southeastern United States.
This includes very southern Virginia to Florida and east
to eastern Texas. There are three subspecies: the eastern,
Florida, and western cottonmouths.
Cottonmouths are semi-aquatic and can be found near water
and fields. They inhabit brackish waters and are commonly
found in swamps, streams, marshes, and drainage ditches
in the southern lowlands of the United States. They also
live at the edges of lakes, ponds, and slow-moving streams
and waters. They sun themselves on the branches, logs, and
stones at the edge of the water.
Diet in the Wild:
Cottonmouths eat both warm and cold-blooded prey, including
other water snakes. Their diet includes fish, frogs, salamander,
lizards, small turtles, baby alligators, birds, small
mammals, and other snakes. Prey such as frogs, fish, and
other snakes are held in the jaws for a
few moments after capture to allow
them to succumb to the venom. Mammals (which are likely
to bite back) are struck and then instantly released. If
the victim flees before the venom takes effect, the cottonmouth
tracks it by scent. It then examines the carcass by touching
it with its tongue to make sure that the prey is dead.
It swallows the prey headfirst. Unlike non-venomous
reptiles, the cottonmouth takes its time when feeding,
perhaps because its prey is dead.
Newborn cottonmouths have a unique predatory technique. They
flick their brightly colored tail tips, which look like worms,
as bait, enticing small frogs or minnows within striking range.
The copperhead is also know to do this.
The cottonmouth is fed mice, rats, and chicks.
The cottonmouth is oviviparous (the eggs develop within the
maternal body without any additional nourishment from the
parent and hatch within the parent or immediately after laying).
Breeding takes place during the spring. It begins with the
male nudging the female's back and sides. This continues for
as long as several hours, until she exposes her tail and opens
her cloaca for copulation. Ovulation takes place only in alternate
years. The gestation period usually lasts from three to four
months. The female produces a litter of up to 12 living young.
Each young is brightly patterned with a yellow tail and is
relatively large, about eight to ten inches long (20 to 25
cm) and .75 inches (2 cm) in diameter.
There is no particular concern about the conservation of
the cottonmouth. Because they are such large and venomous
snakes, they have only a couple of natural enemies. These
include king snakes, great blue herons, and largemouth
bass. Humans are wary of these venomous snakes and try
to kill them, but non-venomous water snakes are often
mistaken for cottonmouths. As a result, more non-venomous
water snakes are killed every year than cottonmouths.
These snakes can cause very severe, and even sometimes fatal,
damage when they bite. But this is very uncommon because
the cottonmouths are normally not very aggressive creatures.
The number of deaths caused by snakebites (all species) every
year in the United States is negligible.
The venom of the cottonmouth is produced by glands that are
located near the point where the upper and lower jaws join.
As the snake strikes and inserts its fangs in the prey,
the muscles surrounding the poison sacs contract and squeeze
the venom along ducts that lead to the base of the fangs.
The venom then travels through the hollow fangs and out
a small opening at the tip of the fangs into the prey.
Total venom replacement actually requires no more than
three weeks, even after being fully depleted. Under natural
conditions the amount of toxin is never significantly diminished.
The venom of the cottonmouth is hemotoxic. This means that
the venom breaks down and destroys blood cells and other
tissues and reduces the ability of blood to coagulate or
clot. Therefore, this results in a hemorrhage throughout
any portion of the circulatory system that is penetrated
This is in contrast to coral snakes, for example, which
have a neurotoxic venom that attacks the central nervous
system of the prey.
These snakes are also called water moccasins.