The Robinson Library >> Science >> Zoology >> Reptiles and Amphibians >> Suborder Serpentes

Angkistrodon piscivorus (aka Water Moccasin)


Adult cottonmouths are black, brown, and olive and have black crossbands down the length of their bodies. The crossbands are usually darker on the outside of the band with a lighter center and are dumbbell shaped. Juvenile cottonmouths have a similar pattern, but have a yellow tip on the end of their tails, brighter overall color, and more distinct crossbands. The head is large and spade-shaped, and there is a dark line through each eye. The mouth of both juvenile and adult is bright white inside, hence the snake's common name.


Cottonmouth threat display

Cottonmouths can grow up to 6 feet in length, but the average is 2 to 4. Males are generally longer and heavier than females, and have they also have more subcaudal scales (enlarged scales on the tail).

Distribution and Habitat

Cottonmouths range from Virginia to western Missouri, from the Florida Keys to western Texas. They prefer wetlands, but are also found on land in vegetation and under logs and branches. Because they are naturally semi-aquatic, they almost always live in close proximity to water; they may also live in bodies of water including bays, salt marshes, lakes, creeks, ditches, and even on river bottoms.


Cottonmouths prey primarily on fish, but they will also take small mammals, frogs, turtles, snakes, eggs, insects, carrion, and birds. Opportunistic feeders, they employ both ambush and active foraging strategies, and are capable of catching and biting prey under water. They catch their food by striking, biting, and releasing venom into the prey. They will also hold the prey in their coils until it is no longer struggling.


Breeding may occur at any time of the year, but most matings occur between April and May.

Male cottonmouths perform a combat dance in which they slither back and forth while waving their tails to lure a female away from competing males. Males also fight each other, with the winner having the right to mate with the female they were competing over. It is believed that breeding pairs are monogamous during the mating season, with new pairs forming each year.

After copulation, female cottonmouths retain the eggs, which develop inside of her for 5 months, after which they give birth to as many as 16 live young (the average is 5-9). The sex of the young is determined through genetics, not the environment. The young stay with the mother for a few days until they are able to move around on their own, after which they are left to fend for themselves. Cottonmouth young suffer high predation rates, with an average of only 2 or 3 per clutch making it to adulthood.

Females reach sexual maturity at three years, males at two years. The average lifespan of cottonmouths in the wild is undocumented, but the oldest cottonmouth known lived to be 24.5 years old.

Habits and Behaviors

Cottonmouths are solitary, and the only times you will see more than one in the same place at the same time are during mating and for the few days after a mother gives birth. They are also territorial, rarely wandering far from their home range (if they leave it at all). The home range size averages 2.5 acres, typically including a water source, such as a river or lake. The size of a cottonmouth's home range tends to increase with the size of the snake and varies with gender. Males typically have significantly larger home ranges.

Cottonmouths are aggressive snakes and will bite when disturbed or provoked. They first give warning signs by shaking their tail back and forth, making a rustling noise, elevating their heads off the ground a few inches, and coiling up while exposing their open white mouth. As a defense mechanism or in a situation when they are threatened they will emit a foul-smelling musk as well.

When swimming, the cottonmouth holds its head above water with most of its body barely touching the surface.

Although cottonmouths will come out during the day to sun themselves, they tend to be most active at night.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Reptilia
order Squamata
suborder Serpentes
family Viperidae
genus & species Angkistrodon piscivorus

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The Robinson Library >> Science >> Zoology >> Reptiles and Amphibians >> Suborder Serpentes

This page was last updated on September 14, 2017.