Agkistrodon piscivorus
cottonmouth
(Also: water moccasin)

Cottonmouths are found throughout the southeastern United States.

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 thes 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.

30 -48 inches in length, occasionally up to 74. 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 by basking. 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. They are very useful, especially when the cottonmouths are feeding on warm-blooded prey such as mammals or birtds that continuously give off a certain amount of body heat. 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 C higher or lower than that of the background. They allow the snakes to strike very accurately at the source of heat. Since both snakes and prey are normally most active at night, when the surrounding air is cooler, then the sensory apparatus is more efficient.

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 after captured for a few moments to allow them to succumb to the venom. Mammals (who 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 examine the carcass by touching it with its tongue to make sure that the prey is dead. Then 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.

These snakes can cause very severe, and even sometimes fatal, damage when they bite. But this is very uncommon since the cottonmouths are normally not very aggressive creatures. The rate of deaths caused by snakebites (all species) every year in the United States is negligible.

There is no particular positive economic importance of these snakes.

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.

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. The venom of the conttonmouth is hemotoxic. This means that the venom breaks down and destroys blood cells and other tissues and lowers the ability to coagulate or clot. Therefore, this results in a hemorrhage throughout any portion of the circulatory system that is penetrated by poison. This is in contrast to the coral snakes, who have a neurotoxic venom that attacks the central nervous system of 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. Toxin is generated continuously according to the individual cyclical output schedules of the five or more types of squarish secretory cells that line the sides of the jaw. Each type of cell generates a separate protein fraction which, by disorganizing first the vascular system of envenomated prey, then its muscle tissue, prepares the carcass for further digestion in the snake's stomach.