2 to 5 feet (0.6 to 1.5 m)
2 to 10 pounds (0.9 to 4.5 kg)



The Water Moccasin, also commonly known as the Cottonmouth (Agkistrodon piscivorus), is a venomous snake native to the southeastern United States. It belongs to the Viperidae family, which includes various species of vipers and pit vipers known for their long, hinged fangs that allow for efficient envenomation. The Cottonmouth is a member of the subfamily Crotalinae, often referred to as pit vipers, characterized by their heat-sensing pit organs located between the eyes and nostrils on each side of the head. These organs enable them to detect warm-blooded prey.

In the Animal Kingdom, the Water Moccasin is classified under the class Reptilia and order Squamata, which encompasses all snakes and lizards. This species is particularly noted for its semi-aquatic nature, inhabiting a range of wetland habitats including swamps, marshes, ponds, and streams. Cottonmouths are highly adapted to aquatic environments and are excellent swimmers.

Distinguished by its stout body, blocky head, and often dark, olive, or brownish coloration, the Water Moccasin can be identified by the white coloration inside its mouth, which is displayed as a defensive warning. They have a varied diet, feeding primarily on fish and amphibians, but they will also consume small mammals, birds, and other snakes.

Renowned for its potent venom, the Cottonmouth is an apex predator in its ecosystem, playing a crucial role in controlling the populations of its prey species. Despite its fearsome reputation, the Water Moccasin is generally a shy species, preferring to avoid conflict with humans. Their presence in diverse wetland habitats highlights their ecological importance and the need for the conservation of these vital areas.

Critically Endangered
Near Threatened
Least Concern

Physical Characteristics

The Water Moccasin, also known as the Cottonmouth (Agkistrodon piscivorus), is a venomous snake native to the southeastern United States. It is part of the pit viper family and is renowned for its aquatic lifestyle, living in or near freshwater environments like rivers, lakes, marshes, and swamps. Here’s a detailed look at the physical characteristics of the Water Moccasin:


  • Body Length: Adult Water Moccasins typically range from 2 to 4 feet (0.6 to 1.2 meters) in length, with some individuals reaching up to 5 feet (1.5 meters).
  • Weight: While specific weight data vary, adult snakes can weigh around 2 to 10 pounds (0.9 to 4.5 kilograms), depending on their length and health.

Physical Characteristics

  • Body Shape: Water Moccasins have a heavy, thick-bodied appearance, with a distinctively blocky head wider than the neck and a stout tail.
  • Skin and Coloration: Juveniles have a bright, contrasting pattern of dark bands on a lighter background, which fades as they mature into a more uniform dark brown, olive, or nearly black color. Adults retain a faint banding pattern that can be seen in certain lighting. The interior of the mouth is distinctively white, which is a defensive display, hence the name “Cottonmouth.”
  • Head: The head shows a prominent pit between the eye and the nostril on each side, part of their heat-sensing system used to detect warm-blooded prey. Their eyes have vertical pupils, unlike the round pupils of non-venomous water snakes.
  • Scales: The scales are keeled, giving them a slightly rough texture. The body is covered in these scales, which help camouflage the snake in its natural environment.
  • Fangs: As a venomous snake, Water Moccasins have long, hollow fangs that they use to inject venom into their prey. These fangs are located at the front of the mouth and can be folded back when not in use.

Behavior and Adaptations

  • Habitat: True to their name, they are semi-aquatic and thrive in water-rich environments. They are excellent swimmers and are often found basking on branches or stones near water.
  • Defense: When threatened, Water Moccasins may display their mouth, showing the white interior as a warning. If further provoked, they can deliver a potent venomous bite. However, they prefer to avoid confrontation and will typically flee from humans if given the opportunity.

Water Moccasins’ adaptations to their aquatic environment, venomous bite, and distinctive appearance make them a unique species within the viper family. While they are often feared due to their venom, they play an essential role in controlling the populations of their prey and maintaining the balance of their ecosystems.


The Water Moccasin, or Cottonmouth (Agkistrodon piscivorus), follows a distinctive reproductive cycle:


Water Moccasins typically mate in the spring, though mating can occur in the fall as well. Males locate females by following pheromone trails and may compete with other males for mating opportunities.


After mating, the female undergoes a gestation period. This gestation period for Water Moccasins is typically around three to four months. However, it can vary based on environmental conditions and the health of the female.


Water Moccasins are ovoviviparous, meaning they give birth to live young. The embryos develop inside the mother’s body, nourished by yolk sacs, and then are born fully formed. This method of reproduction is advantageous in their aquatic environments, as it eliminates the need to lay and protect eggs in a terrestrial setting.

The number of offspring can vary, typically ranging from 6 to 12 young, but larger litters are possible.


Newborn Water Moccasins are independent from birth, and equipped with venom and fangs. They are capable of hunting and fending for themselves almost immediately.

The reproductive cycle of the Water Moccasin, particularly its live birth, is a fascinating aspect of their biology. This reproductive strategy ensures a higher survival rate for the offspring, as they are born mobile and capable of defending themselves in their aquatic and sometimes precarious environments.


The Water Moccasin, or Cottonmouth (Agkistrodon piscivorus), has a notable lifespan, which varies depending on whether it is in the wild or in captivity:

Lifespan in the Wild:

In their natural habitats, Water Moccasins typically live for about 10 to 15 years. However, this can vary based on factors such as availability of food, environmental conditions, and predation.

Lifespan in Captivity:

In captivity, where they are protected from predators and have consistent access to food and medical care, Water Moccasins can live longer. They often reach ages of 15 to 20 years, and in some cases, they may live beyond 20 years in zoological parks or reptile sanctuaries.

Major Threats:

  1. Habitat Loss: Urbanization and development can lead to the loss of wetland habitats, impacting the Water Moccasin’s natural hunting and breeding grounds.
  2. Human Conflict: Due to their venomous nature, Water Moccasins are often feared and persecuted by humans. They are sometimes killed on sight, particularly in areas close to human habitation.
  3. Pollution: Pollution of water bodies can affect their health and reduce the availability of prey species.
  4. Climate Change: Changes in climate patterns can impact their wetland habitats, affecting their ability to find suitable breeding and hunting areas.

Conservation efforts for Water Moccasins involve protecting and preserving wetland habitats and educating the public about their ecological role as controllers of rodent and amphibian populations. Understanding their importance in maintaining ecological balance in wetland ecosystems is crucial for their conservation.

Eating Habits

The Water Moccasin, also known as the Cottonmouth (Agkistrodon piscivorus), has specific eating habits that are well-suited to its semi-aquatic lifestyle:


Variety in Prey: Water Moccasins have a diverse diet. They primarily feed on fish and amphibians, but they also consume small mammals, birds, small turtles, baby alligators, and other snakes. Juveniles often feed on insects and small fish.

Hunting Techniques:

Ambush Predation: The Water Moccasin is primarily an ambush predator. It waits motionless near the water’s edge or partially submerged, striking quickly when prey comes within range.

Chasing Prey: It is also capable of actively chasing prey in the water, using its strong swimming ability.

Venomous Bite: When it catches larger prey, the Water Moccasin uses its potent hemotoxic venom to immobilize it. The venom also aids in the digestion of the prey.

Feeding Behavior:

Swallowing Whole: Like most snakes, the Water Moccasin swallows its prey whole. Its flexible jaws can expand to consume prey larger than its head.


Water Moccasins are adaptable in their feeding habits, allowing them to thrive in a variety of wetland habitats. Their ability to consume a wide range of prey items is key to their survival in these environments.

The Water Moccasin’s feeding habits demonstrate its role as an effective predator in its ecosystem. By controlling populations of fish, amphibians, and rodents, it helps maintain ecological balance in the wetlands and adjacent areas it inhabits.


The Water Moccasin, or Cottonmouth (Agkistrodon piscivorus), possesses several unique characteristics that set it apart from other snake species:

1. Semi-Aquatic Nature: As a semi-aquatic snake, the Water Moccasin is equally adept at living in water and on land. It is one of the few North American venomous snakes that can be found often in and around water bodies like streams, swamps, and ponds.

2. Defensive Behavior: When threatened, the Water Moccasin is known for its distinctive defensive behavior. It often opens its mouth wide to display the white interior (hence the name “Cottonmouth”), and vibrates its tail as a warning.

3. Venomous Bite: The Water Moccasin has a potent hemotoxic venom, which is effective in subduing prey and serves as a defense mechanism. It’s one of the few snakes in its region with such a potent venom.

4. Diet: It has a varied diet and can consume a wide range of prey, including fish, amphibians, small mammals, birds, and other reptiles. This adaptability in feeding habits allows it to thrive in diverse environments.

5. Locomotion: On land, the Water Moccasin moves with a distinctive, heavy, rolling gait. In water, it swims with its body floating, which is different from many other snakes that swim with their bodies submerged.

6. Reproductive Strategy: The Water Moccasin is ovoviviparous, giving birth to live young, which is relatively rare among snakes and a notable adaptation to its aquatic habitat.

7. Camouflage: Its dark, band-like coloration provides excellent camouflage in its natural habitat, aiding in both predation and protection from predators.

These characteristics make the Water Moccasin a unique and fascinating species, particularly adapted to life in wetland ecosystems. Its role as a predator and its distinctive traits contribute significantly to the biodiversity and ecological balance of its habitat.


1. How long can the water moccasin stay underwater?

The Water Moccasin, also known as the Cottonmouth (Agkistrodon piscivorus), is a semi-aquatic venomous snake that is adept at swimming and capable of staying underwater for extended periods. While the exact duration can vary, Water Moccasins can typically remain submerged for about 10 to 30 minutes.

This ability to stay underwater is an adaptation to their aquatic lifestyle, allowing them to hunt for prey such as fish and amphibians, escape predators, and avoid detection. Their skill in the water, combined with their ability to hold their breath for significant periods, makes them efficient aquatic predators and helps them thrive in their swampy, marshy habitats.

It’s important to note that while Water Moccasins can stay underwater for a considerable time, they are not exclusively aquatic and spend a good deal of time on land or basking in the sun on branches, rocks, or logs near water bodies.

2. What other snake is most like the Water Moccasin?

The snake most similar to the Water Moccasin, or Cottonmouth (Agkistrodon piscivorus), is the Copperhead (Agkistrodon contortrix). Both belong to the same genus, Agkistrodon, and share several characteristics:

1. Venom: Both the Water Moccasin and the Copperhead are venomous, possessing a hemotoxic venom that can cause significant tissue damage. However, the venom is generally less toxic compared to that of some other venomous snakes, like rattlesnakes or coral snakes.

2. Habitat: While the Water Moccasin is more aquatic, both species thrive in a variety of habitats, including forests, wetlands, and near bodies of water. Copperheads, however, are more commonly found in terrestrial and wooded areas.

3. Behavior: Both snakes exhibit a similar behavior when threatened, often freezing in place rather than fleeing, relying on their camouflage to avoid detection. They can be aggressive when provoked but generally prefer to avoid confrontation.

4. Physical Appearance: While their coloration patterns differ, both species have a distinctive pit viper appearance, with thick, heavy bodies and broad, triangular heads.

5. Reproduction: Both the Water Moccasin and the Copperhead are ovoviviparous, giving birth to live young rather than laying eggs.

6. Diet: Both snakes have a varied diet, primarily feeding on small rodents, amphibians, and other small animals.

The similarities between these two snakes can often lead to confusion in identification, especially in overlapping habitats. However, their distinctive coloring and preferred habitats are key identifiers. Understanding these similarities and differences is important for proper identification and awareness, especially in regions where they are common.

  • Britannica, Moccasin, https://www.britannica.com/animal/moccasin-snake, retrieved January 2024.
  • Burnie, David & Wilson, Don, Animal, Smithsonian Institute, Washington DC.
  • Hickman et al, Integrated Principle of Zoology, McGraw Hill, Boston.