The Rainbow Snake Feasts on American Eels

If you take a close enough look at many different snake skins, you'll catch this iridescent sheen. But this is different from the pattern on Farancia erytrogramma, the real rainbow snake. Iuliia Tarabanova / Shutterstock

The rainbow snake (Farancia erytrogramma) — sometimes called an eel moccasin or red-lined snake — is a nonvenomous snake. It has vibrant coloration and a specialized diet. Humans rarely see rainbow snakes (despite their striking appearance) because they spend much of their lives hidden in aquatic habitats.

These creatures primarily live in the southeastern United States, where they inhabit swamps, rivers and other freshwater environments. Their secretive nature and unique behaviors make them a subject of interest for herpetologists and reptile enthusiasts alike.

Physical Characteristics of Rainbow Snakes

Rainbow snakes have stunning coloration, which gives them their name. Adult rainbow snakes have a glossy, black or dark blue back with three red stripes running the length of their bodies. The underside of the snake is typically yellow or red with black spots.

Juvenile rainbow snakes have similar coloration but may be more vibrant.

Male rainbow snakes tend to be smaller and slimmer than females, but both sexes share the same colorful appearance. The common rainbow snake can grow to relatively impressive lengths, often reaching 3 to 4 feet (0.914 to 1.22 meters), with some growing even longer.

Subspecies of Rainbow Snakes

There are a couple recognized subspecies of the rainbow snake, with the most well-known being the common rainbow snake and the southern Florida rainbow snake.

Common Rainbow Snake

The common rainbow snake lives throughout the southeastern United States. Known for its iridescent, rainbow-like scales, this snake primarily inhabits freshwater environments such as swamps, marshes and slow-moving rivers.

It feeds on aquatic prey — especially eels — making it a key player in the local ecosystem. The rainbow snake poses no threat to humans and is a protected species in some areas due to habitat loss.

Southern Florida Rainbow Snake

The southern Florida rainbow snake is native to a more restricted range in South Florida, and it may even be extinct. (The last confirmed specimen was collected in 1952, but there have been unconfirmed sightings in the years since.)

Social Habits of Rainbow Snakes

Rainbow snakes are solitary creatures, coming together only during the breeding season. They are highly secretive and spend most of their time hidden in aquatic habitats.

Unlike many other snakes, rainbow snakes are not commonly seen basking in the sun; instead, they are under logs, debris or in the water itself. These snakes are primarily nocturnal, becoming active at night to hunt and explore their environment.

The Rainbow Snake Diet

Rainbow snakes have a specialized diet that primarily consists of eels, earning them the nickname "eel moccasins." The skilled hunters often consume their prey alive. Rainbow snakes eat a variety of aquatic prey, but eels make up the bulk of their diet, particularly the American eel.

Young rainbow snakes may also consume smaller prey such as tadpoles and small fish. The snake’s slender body and sharp teeth allow it to catch and hold onto slippery, wriggling prey in the water.

Rainbow Snake Environment

Rainbow snakes spend most of their lives in aquatic habitats. They primarily live in freshwater environments, such as rivers, streams, swamps and marshes, particularly in areas with dense vegetation and plenty of hiding spots.

These habitats provide the cover and resources rainbow snakes need to thrive, including their preferred prey.

The snakes are excellent swimmers, using their long, muscular bodies to navigate through the water with ease. They are rarely far from water and rely heavily on these aquatic ecosystems for survival.

Life Cycle of Rainbow Snakes

The life cycle of a rainbow snake begins with the mating season, which occurs in the spring. After mating, female rainbow snakes lay their eggs in concealed, moist locations such as under logs, in sand or within rotting vegetation near water.

A typical clutch can contain anywhere from 10 to 50 eggs, depending on the size of the female. The eggs incubate for several months before hatching in late summer or early fall.

Young rainbow snakes are independent from birth, though they remain hidden and vulnerable during their early stages of life. As they grow, juvenile rainbow snakes gradually develop the vibrant coloration that characterizes adult rainbow snakes.

Conservation Status

Rainbow snakes are not currently considered endangered, though the southern Florida rainbow snake may be extinct. Rainbow snake populations are vulnerable to habitat destruction and pollution, particularly in areas where there are threats to freshwater ecosystems.

While not as well-known as other species, such as eastern indigo snakes, rainbow snakes play an important role in their ecosystems and are a fascinating species worth conserving. Conservation efforts focus on preserving the aquatic habitats that are crucial for the survival of these snakes and protecting them from the impacts of human activities.

We created this article in conjunction with AI technology, then made sure it was edited and fact-checked by a HowStuffWorks editor.