Semi-aquatic snakes can be found all over the world, including North Carolina. Of the 38 species of snake in North Carolina, 11 are semi-aquatic, with one subspecies being found only in the state. Semi-aquatic snake species may spend time on land, but get the vast majority of their food from aquatic prey, often specializing in specific types (such as the aptly named crayfish snakes).
Several more species can be semi-aquatic at different times or places. Many snake species, such as the copperhead, are generalists, and individuals or local populations can vary considerably in how much time is spent in water, depending on the temporal and spatial variation in food, competition, and climate.
North Carolina is generally divided geographically into three sections from east to west: the low-lying Coastal Plain, which abuts the Atlantic Ocean and is full of swamps and wetlands, the Piedmont (or foothills) in the center of the state, with low rolling hills, plenty of large, slow rivers but few wetlands, and the Appalachian Mountains in the far west, with smaller rivers and little slow-moving water. A snake’s preferred aquatic habitat and prey (or a lack of a preference) can generally tell you in which part of the state you’re likely to find it. What follows is a description of the semi-aquatic snakes found in North Carolina.
North Carolina Water Snakes
1) Northern cottonmouth
- Scientific name: Agkistrodon piscivorus
- Meaning of scientific name: ‘Hook-toothed fish eater’
- Family: Viperidae
- Subfamily: Crotalinae
- Other names: Water moccasin, black moccasin, North American cottonmouth snake
- Average adult length: 3 – 4 ft (90 – 120 cm)
- Maximum adult length: 6 ft (180 cm)
- Threatened status: Least Concern
The northern cottonmouth, also commonly called the water moccasin, is a medium-sized, venomous pit viper. It gets its name from its milky-white mouth which it displays as a fear or threat response. It is the only venomous semi-aquatic snake in North America, and one of six venomous snakes found in North Carolina. Snakes cannot chew their food – they must swallow it whole.
Most snakes thus consume food that is smaller than their head or that doesn’t put up much of a fight. A few snakes, however, have evolved the means to incapacitate larger or more slippery prey, through either constriction (such as boas) or venom (such as the cottonmouth). The cottonmouth will eat just about anything that it can swallow, mainly fish and amphibians, but also small mammals, and other reptiles – even small alligators.
It prefers warmer marshes and slow-moving rivers, and is found only in the eastern half of North Carolina, as part of a range that follows the coastal plain from Virginia to central Texas, and up the Mississippi and its tributaries north to southern Illinois. Its coloration can vary from light brown to almost black, and like copperheads (which are also pit vipers), can be identified by ‘Hershey’s kisses’ type markings along its length. Though they are venomous, cottonmouths are not very aggressive. Bites are rare and are usually a result of being (mis)handled. Despite this, they are widely feared, and many other semi-aquatic snakes in this region are misattributed as cottonmouths. They can be distinguished from the much more common water snake in a number of different ways found here.
2) Northern water snake
- Scientific name: Nerodia sipedon
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Common water snake, banded water snake, North American water snake
- Average adult length: 2.75 ft (85 cm)
- Maximum adult length: 5 ft (150 cm)
- Threatened status: Least Concern
The northern or common water snake is relatively small and is the most commonly sighted water snake in North Carolina. They are found throughout North Carolina except the southern Coastal Plain, and while they prefer slow-moving bodies of water, they can be found in just about any aquatic environment, including mountain streams.
Their colors can vary from gray, brown, black, or red, with dark repeating blotches. While it is commonly mistaken for the cottonmouth due to its coloration, they are harmless to humans, and will only bite if they are grabbed or captured. They can sometimes be seen resting in trees by or over the water and have been known to fall into people’s boats. They prey mostly on small fish and amphibians.
Females tend to be larger than males, as is the case in around two-thirds of snake species. This is due to females needing to develop and carry offspring, and the infrequency of male-to-male combat in many snake species, which, when present, favors the evolution of larger males. Like many aquatic and semi-aquatic snake species, the common water snake is ovoviviparous, meaning its eggs hatch internally and it gives birth to live young. This is likely an adaption to their aquatic environment, as snake eggs need to stay mostly dry to avoid fungal and microbial growth.
A darker-colored subspecies of the common water snake, the Carolina water snake, is found only along the North Carolina coast, where it usually inhabits brackish waters.
3) Plainbelly water snake
- Scientific name: Nerodia erythrogaster
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Plain-belly water snake, redbelly water snake, yellowbelly water snake
- Average adult length: 3.25 ft (100 cm)
- Maximum adult length: 5 ft (150 cm)
- Threatened status: Least Concern
The plainbelly water snake is another of the four species of Nerodia snakes (water snakes) found in North Carolina. The particular subspecies there is Nerodia erythrogaster erythrogaster, or the ‘red-bellied water snake,’ named after its red (as opposed to cream) belly. Subspecies often arise when a species has a large geographic extent, but populations breed locally.
As with much of taxonomy, the line between what constitutes a subspecies as opposed to just intra-species variation is often unclear. Some researchers don’t recognize N. erythrogaster as having subspecies, due to a lack of genetic and ecological diversity.
Unlike the common water snake, the plainbelly water snake is found almost exclusively in wetlands, and as such it only inhabits the eastern half of North Carolina. It tends to travel overland further than other water snakes and is often encountered on roads. The young are usually blotched but adults have a solid dark back with a lighter underbelly (brown and red respectively in the North Carolina variant).
Like other water snakes, the end of its tail is often missing, which is likely caused by the tail drying out during winter hibernation or being bitten off as they dangle in trees. Like other water snakes, the plainbellied gives off a foul-smelling odor when threatened, but whereas the common water snake is apt to flee, plainbelly water snakes prefer to give a threat response, and will bite if provoked.
4) Banded water snake
- Scientific name: Nerodia fasciata
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Southern water snake
- Average adult length: 2.75 ft (85 cm)
- Maximum adult length: 5 ft (150 cm)
- Threatened status: Least Concern
This medium-sized water snake that inhabits North Carolina’s coastal plain is named after the crossbands that run the length of its body. The banded water snake exhibits a high degree of color variation, even in local populations, from red to brown to black. As they age, some of these snakes darken in color and are mistaken for cottonmouths, as is common for most semi-aquatic snakes that overlap with the cottonmouth’s range.
Snake identification based on coloration and size is very tricky, as both of these factors can vary greatly for a single species. Amateurs are encouraged to focus on color patterns. For more accurate species identification, biologists also rely on details in the size, location, pattern, and number of scales on different parts of a snake’s body, especially the head. Dichotomous keys are extremely helpful in this regard.
As in all other water snakes, N. fasciata gives birth to live young, emits a musk when threatened, consumes mainly fish and amphibians, and displays sexual dimorphism, with females being larger than the males. As is common for semi-aquatic snakes in the southeastern United States, the banded water snake has three subspecies – one along the coastal plain from Virginia to Georgia, one in Florida, and one in the Mississippi River delta and floodplain, and eastern Texas. These are known as the banded water snake, the Florida water snake, and the broad-banded water snake, respectively.
5) Brown water snake
- Scientific name: Nerodia taxispilota
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Aspic, false moccasin, great water snake
- Average adult length: 3.5 ft (105 cm)
- Maximum adult length: 5.75 ft (175 cm)
- Threatened status: Least Concern
The fourth and largest species of Nerodia in North Carolina is the brown water snake. It has alternating dark brown blotches along its brown body, and compared to other semi-aquatic snakes, shows little variation in coloration. Unlike other members of its genus, the brown water snake mainly eats fish, particularly catfish, and its larger body size is an adaptation to larger prey.
Body size and diet are often highly linked in animals. It is difficult for large predators to satisfy their caloric requirements by focusing on small prey, and ones that do are often highly specialized and focus on prey that are particularly abundant (such as anteaters, ants, baleen whales, and krill).
The brown water snake’s larger size and diet mean it is found in larger bodies of water such as rivers, wetlands, and reservoirs, thus it only occurs in the eastern half of North Carolina. Its size also causes it to be misidentified as a cottonmouth and is subsequently killed in large numbers by humans. Despite this, and its lower population size than other water snakes (again due to its body size), it has thriving populations throughout its range of the Atlantic Coastal Plain and Florida.
6) Queen snake
- Scientific name: Regina septemvittata
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Brown queen snake, olive water snake, queen water snake, moon snake
- Average adult length: 1.75 ft (55 cm)
- Maximum adult length: 3 ft (90 cm)
- Threatened status: Least Concern
Members of the genus Regina are known as crayfish snakes due to their preferred prey. The queen snake visually resembles the common garter snake, being gray with a white strip running down each side. They prefer mountain streams where crayfish are abundant among submerged rocks and thus are only found in the western half of the state.
Crayfish have a hard carapace, and while some crayfish snakes will eat any crayfish, the queen snake preys only on those that are molting. A crayfish’s exoskeleton can’t grow with the rest of the body, so the animal periodically hides, sheds its shell, expands, and then waits for the new carapace to harden.
The queen snake has evolved the ability to smell this fresh soft carapace, allowing it to hunt crayfish in their most defenseless state. The queen snake can be found anywhere where freshwater crayfish are abundant in Appalachia and the eastern Midwest. As such, the degradation of rocky habitats needed for crayfish has severely reduced its population in certain areas, such as Pennsylvania.
7) Glossy crayfish snake
- Scientific name: Liodytes rigida or Regina rigida
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Eastern glossy swampsnake, crayfish snake
- Average adult length: 1.5 ft (45 cm)
- Maximum adult length: 2.5 ft (75 cm)
- Threatened status: Least Concern
The glossy crayfish snake is very similar in appearance to the queen snake, though its lateral bands are not bright and conspicuous, but dark and difficult to see against its brown to olive body. It also has two bands of dots along its white to yellow belly.
Many biologists believe that it should be classified in the same genus as the queen snake, Regina, and you will see it variously referred to as either Regina rigida or Liodytes rigida. As its name suggests, it also feeds almost exclusively on crayfish, preferring burrowing crayfish of marshes and wetlands, and is thus only found in the far east of the state in the lowland Coastal Plain.
Unlike the queen snake, the glossy crayfish snake will feed on any crayfish, not just molting ones, and it has sharp flat teeth that help it puncture and hold on to its prey. Non-molting crayfish can put up a fight against smaller snakes, with their chelicerae (pincers) in the front, and powerful tail in the rear, so the glossy crayfish snake tends to attack crayfish from the side, biting them until they die, and then swallowing them whole tail end first.
Often an animal’s biggest competition is other members of its own species, as they have the same needs and will vie for the same finite resources, be it food, reproduction, or habitat. This is also true for different species that want the same resource. For crayfish snakes in North Carolina, the two species avoid competition by specializing in different crayfish habitats – wetlands versus flowing water – and their ranges don’t overlap. Speciation often occurs due to animals evolving to use different parts of the environment, thus ‘opening’ up new resources.
8) Carolina swamp snake
- Scientific name: Liodytes pygaea paludis
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Black swamp snake, mud snake, swamp snake
- Average adult length: 13 in (33 cm)
- Maximum adult length: 21 in (53 cm)
- Threatened status: Special Concern in North Carolina
This small semi-aquatic snake is found along the coastal lowlands of North Carolina, South Carolina, Georgia, and throughout the whole state of Florida. They have a shiny black back and a strikingly red to red-orange belly. Their prey tends to be smaller than the previously listed snakes, and consist mainly of leeches, tadpoles, aquatic worms, and sirens (tiny legless salamanders).
The Carolina swamp snake prefers slow-moving or stagnant water and is often found in areas of dense aquatic vegetation, where its prey is more abundant. When found, the snake is often present in abundance, but they are highly secretive and patchily distributed throughout their range, so little is known of their behavior and population size.
It is also highly dependent on wetland ecology and is sometimes called North Carolina’s most aquatic snake. Due to these reasons, it is of conservational concern throughout most of its range. The Carolina swamp snake, L. pygaea paludis, is one of three subspecies of the black swamp snake L. pygaea. The other two are found in Florida.
9) Eastern ribbon snake
- Scientific name: Thamnophis saurita saurita
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Ribbon snake, common ribbon snake, water garter snake
- Average adult length: 1.75 ft (55 cm)
- Maximum adult length: 3.75 ft (115 cm)
- Threatened status: Least Concern
The eastern ribbon snake is one of four subspecies of the ribbon snake, a close relative to the common garter snake, of which they bear a close resemblance and are easily mistaken for. Their back is brown to black, with three yellow to cream stripes running their length. They prey mainly on fish and amphibians, and can often be found basking in trees either over water or land. They are found throughout the state but are rare in Appalachia.
Ribbon snakes are adapted for both terrestrial and aquatic life – they spend a significant amount of time on land, but are always found near water and are excellent swimmers, as they prey almost exclusively on aquatic animals. The North Carolina Wildlife Resources Commission does not include them in their list of aquatic snakes, while the Virginia Herpetological Society does, which illustrates the fuzzy boundary of how semi-aquatic a snake should be before it is considered aquatic.
Ribbon snakes are harmless to humans, common throughout their range, and easy to study. As such, they are sometimes used to study the health of wetland ecosystems. Being predators several levels up the food chain, ribbon snakes will bioaccumulate toxins from the environment.
10) Eastern mud snake
- Scientific name: Farancia abacura
- Family: Colubridae
- Subfamily: Dipsadidae
- Other names: Mud snake, western mud snake, checkered snake, hoop snake, red-bellied mud snake
- Average adult length: 3.5 ft (105 cm)
- Maximum adult length: 6.5 ft (200 cm)
- Threatened status: Least Concern
The mud snake, together with the rainbow snake, comprise the genus Farancia. Both species are found throughout the lowlands of the southeastern United States (including the Coastal Plain of North Carolina) and are relatively large, glossy, tubular, semi-aquatic species. The mud snake is divided into eastern and western subspecies, the eastern being present in North Carolina.
It is one of the largest aquatic snakes in the area, however it is both nocturnal, extremely secretive, and is subsequently rarely ever seen. It almost never leaves the water, except to lay eggs (which can sometimes be found in old alligator nests) or to hibernate. It has been described by some as “fully aquatic,” though not everyone agrees.
It has a very distinctive coloration, with a black back and bright red bands on its belly. It preys almost exclusively on amphibians, particularly amphiumas and sirens; two families of large, elongated aquatic salamanders that resemble eels. It prefers slow-moving water and wetlands, particularly environments with robust aquatic vegetation.
The mud snake is one of the sources of the ‘hoop snake’ myth, a legend that these snakes would bite their tail, roll into a ball, and chase people. They are also sometimes referred to as the stinging snake, as the end of its tail is pointed. It uses this to stab prey, but not people.
11) Rainbow snake
- Scientific name: Farancia erytrogramma
- Family: Colubridae
- Subfamily: Dipsadidae
- Other names: Common rainbow snake, horned snake, mud snake, eel moccasin
- Average adult length: 3 ft (90 cm)
- Maximum adult length: 5.5 ft (170 cm)
- Threatened status: Least Concern
The final aquatic snake found in North Carolina is the sister species of the mud snake. They are extremely similar in size, shape, behavior, and preferred habitat, and differ mainly in coloration and diet. The rainbow snake has a beautiful striped pattern, with alternating lines of black, red, and yellow running the length of its body.
They feed mainly on the freshwater American eel, and thus avoid resource competition with the mud snake, as they inhabit the same coastal lowlands of North Carolina. A subspecies of the rainbow snake used to be present in the Lake Okeechobee region of Florida but was declared extinct in 2011.
