Water Moccasin

## Description

The Water moccasin (Agkistrodon piscivorus) is a species of venomous pit viper. It is one of the world's few semiaquatic vipers (along with the Florida cottonmouth) and is native to the southeastern United States. As an adult, it is large and capable of delivering a painful and potentially fatal bite. Many of its common names refer to the threat display, in which the Water moccasin will often stand its ground and gape at an intruder, exposing the white lining of its mouth. Many scientists dislike the use of the term water moccasin since it can lead to confusion between the venomous cottonmouth and non-venomous water snakes.

## Appearance

Water moccasins are almost or even totally black, (with the exception of the head and facial markings), the color pattern may consist of a brown, gray, tan, yellowish-olive, or blackish ground colors, which is overlaid with a series of 10-17 dark brown to almost black crossbands. The underside of the head is generally whitish, cream, or tan.

## Distribution

Water moccasins are found in the eastern US from the Great Dismal Swamp in southeast Virginia, south through the Florida peninsula and west to Arkansas, eastern and southern Oklahoma, and western and southern Georgia (excluding Lake Lanier and Lake Allatoona). Their range also includes the Ohio River Valley as far north as southern Indiana, and they inhabit many barrier islands off the coasts of the states where they are found. These snakes are usually associated with bodies of water, such as creeks, streams, marshes, swamps, and the shores of ponds and lakes. They are also found in brackish-water habitats and are sometimes seen swimming in saltwater. Water moccasins are not limited to aquatic habitats. In various locations, these snakes are well-adapted to less moist environments, such as palmetto thickets, pine-palmetto forest, pine woods in East Texas, pine flatwoods in Florida, eastern deciduous dune forest, dune and beach areas, riparian forest, and prairies.

## Behavior

Water moccasins are solitary creatures. They may be active during the day and at night. However, on bright, sunny days, they are usually found coiled or stretched out somewhere in the shade. In the morning and on cool days, they can often be seen basking in the sunlight. They often emerge at sunset to warm themselves on the warm ground (i.e., sidewalks, roads) and then become very active throughout the night, when they are usually found swimming or crawling. Contrary to popular belief, they are capable of biting while underwater. In the north, Water moccasins hibernate during the winter. In the southern parts of their range, hibernation may be short or omitted altogether. For hibernation, these snakes use rocky wooded hillsides, burrows of crayfish, tortoises or other mammals, under rotting stumps or other covers. When stressed or threatened, Water moccasins perform a characteristic threat display that includes vibrating their tail and throwing their head back with their mouth open to display the startling white interior; they will often make a loud hiss while the neck and front part of the body are pulled into an S-shaped position. Many of their common names, including "cottonmouth" and "gaper", refer to this behavior. The habit of Water moccasins to snap their jaws shut when anything touches their mouth has earned them the name "trap jaw" in some areas. Other defensive responses can include flattening the body and emitting a strong, pungent secretion from the anal glands located at the base of the tail.

## Venom

The venom of the Water moccasin is toxic and is rich with powerful cytotoxic venom that destroys tissue. Although deaths are rare, the bite can leave scars, and on occasion, require amputation. Absent an anaphylactic reaction in a bitten individual, however, the venom does not cause systemic reactions in victims and does not contain neurotoxic components present in numerous rattlesnake species. Bites can be effectively treated with CroFab antivenom; this serum is derived using venom components from four species of American pit vipers (the eastern and western diamondback rattlesnakes, the Mojave rattlesnake, and the cottonmouth).

Bites from the cottonmouth are relatively frequent in the lower Mississippi River Valley and along the coast of the Gulf of Mexico, although fatalities are rare. Symptoms commonly include ecchymosis and swelling. The pain is generally more severe than bites from the copperhead, but less so than those from rattlesnakes (*Crotalus spp.* ).

## Diet

Water moccasins are carnivores and their diet includes mammals, birds, amphibians, fish, frogs, snakes, small turtles, and small alligators. On occasion, juveniles feed on invertebrates. These snakes are opportunistic feeders and sometimes eat carrion, making them one of the few snakes to do so.

## Reproduction

It is suggested that Water moccasins are monogamous; this means that during the breeding season a male mates with only one female. Mating occurs in April-May and the young are usually born in August or September. During the mating season, males perform a combat dance and also compete for access to females. Water moccasins are ovoviviparous, with females giving birth to 1-16 live young and possibly as many as 20. However, litters of 6 to 8 are the most common. The gestation period lasts around 4-5 months. Neonates are 22-35 cm in length (excluding runts) and independent at birth. If weather conditions are favorable and food is readily available, growth is rapid and females may reproduce at less than 3 years of age and a total length of as little as 60 cm.

## Population

### Threats

There are no major threats to Water moccasins at present. However, they suffer locally from persecution and habitat destruction through wetland drainage for agriculture, residential and commercial development.

### Number

According to IUCN, the Water moccasin is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.

### Ecological niche

Water moccasins are important for the environment as they control the populations of their main prey, including fish, frogs, turtles, snakes and other reptiles.

## Fun Facts

The generic name of Water moccasins is derived from the Greek words ancistro (hooked) and odon (tooth), and the specific name comes from the Latin piscis (fish) and voro (to eat); thus, the scientific name translates to "hooked-tooth fish-eater".

This is the world's only semiaquatic viper, usually found in or near water. The snake is a strong swimmer and has even been seen swimming in the ocean. However, it is not fully marine, unlike true sea snakes.

Young Water moccasins generally have a more contrasting color pattern than adults; they have dark crossbands on a lighter ground color. The ground color is then tan, brown, or reddish-brown. The tip of their tail is usually yellowish, becoming greenish-yellow or greenish in subadults, and then black in adults. On some juveniles, the banding pattern can also be seen on the tail. Young snakes often use their bright tail tips in hunting; they wiggle the tips of their tails to lure prey animals.