Other common names
Diamondback watersnake, Northern diamond-backed watersnake
Most adult diamond-backed watersnakes are about 30-60 inches (76-152 cm) in total length. These stout-bodied snakes are light grayish-brown with a dark chain-like pattern down the entire body. The scales are strongly keeled (each scale has a prominent raised ridge). Juvenile coloration is similar to that described for adults.
Range in Florida
The presence of diamond-backed watersnakes in Florida is based solely on a single specimen collected in Santa Rosa County in the 1950s. Therefore, it is not known whether an established population exists in Florida.
Assessment of risk to people and pets
Non-venomous Diamond-backed watersnakes are not dangerous to people or pets, but they will readily bite to defend themselves. These snakes are not aggressive and avoid direct contact with people and pets. Virtually all bites occur when the snakes are intentionally bothered.
Comparison with other species
Florida Cottonmouth (Agkistrodon conanti) If the head is viewed from above, the eyes of cottonmouths cannot be seen while the eyes of watersnakes are visible. Cottonmouths have vertically elliptical (cat-like) pupils, whereas watersnakes have round pupils. Cottonmouths have a facial pit between the nostril and the eye, whereas watersnakes do not.
Saltmarsh snake (Nerodia clarkii) Saltmarsh waternsnakes often have several dark stripes running down the entire or partial length of the body, and they are usually only found along the coast in saltwater and brackish habitats.
Florida Green Watersnake (Nerodia floridana) Florida green watersnakes are dark green and have scales between the eye and the scales on the upper lip.
Midland Watersnake (Nerodia sipedon pleuralis) Midland watersnakes have fewer than 30 darker brown crossbands near the neck, which break up into alternating blotches further down the body, and the belly is yellowish marked with two rows of half-moons.
Southern Watersnake (Nerodia fasciata) Southern waternsnakes have broad black, brown, or red crossbands (often bordered with black) down the back and a dark stripe that extends from the eye to the angle of the jaw.
Most adult diamond-backed watersnakes are 30-48 inches (76-122 cm) in total length, with a record length of 69 inches (175.3 cm). These stout-bodied snakes are light grayish-brown with a dark chain-like pattern down the entire body. The distinctive pattern consists of dark blotches running down the middle of the back that are connected to the alternating rows of dark blotches running down the sides by short diagonal lines. The belly is yellowish with dark half-moons. The scales are strongly keeled (each scale has a prominent raised ridge), and there are 25-31 scale rows at midbody. The pupil is round. Juvenile coloration is similar to that described for adults.
In other parts of their range, diamond-backed watersnakes can be found in a wide variety of freshwater habitats. However, they prefer bodies of water with overhanging vegetation.
When approached, diamond-backed watersnakes will typically flee into the water, dive below the surface, and swim away. If grabbed or pinned, they will typically bite the attacker and release a foul-smelling musk from a pair of glands in the base of the tail. Nonetheless, these snakes are not aggressive, and striking is only used in defense as a last resort.
Diamond-backed watersnakes feed almost exclusively on freshwater fishes and frogs. These snakes are not constrictors and overpower their prey by grabbing it in their jaws, hauling it to shore, and swallowing it after it has been subdued. Diamond-backed watersnakes are typically nocturnal (active at night), but they may become more diurnal (active during the day) during the spring and fall.
In other parts of their range, females typically give live birth to 8-62 young between August and September.
Three subspecies of diamond-backed watersnakes are currently recognized, with only one occurring in Florida
- Northern diamond-backed watersnake (Nerodia rhombifer rhombifer)
Unfortunately, many watersnakes are killed every year by Florida residents who mistake them for cottonmouths. Although cottonmouths occur throughout Florida, they are not nearly as abundant as the eight species of harmless watersnakes (species in the genus Nerodia) that occur in much the same habitats. If you see a snake in or near the water, most likely it is a harmless watersnake, and it is best to simply leave it alone.
If you have a new or interesting observation for this species, please email the herpetology staff at the Florida Museum.
Ernst, C.H. and E.M. Ernst. 2003. Snakes of the United States and Canada. Smithsonian Institution Press, Washington, DC. 668 pp.
Gibbons, J.W. and M.E. Dorcas. 2004. North American Watersnakes: A Natural History. University of Oklahoma Press, Norman, Oklahoma. 438 pp.
Krysko, K.L., K.M. Enge, and P.E. Moler. 2019. Amphibians and Reptiles of Florida. University of Florida Press, Gainesville, Florida. 706 pp.
Powell, R., R. Conant, and J.T. Collins. 2016. Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America. Fourth edition. Houghton Mifflin Harcourt Publishing Company, Boston and New York. xiv + 494 pp.
Share your observations
You can help scientists better understand the biology and distribution of this species by sharing your observations. Send photos or videos of interesting observations, along with associated information, by emailing the herpetology staff at the Florida Museum for documentation in the Museum’s Herpetology Master Database. You can also post your observations on iNaturalist.
Additional helpful information
Do you have snakes around your house? Learn how to safely co-exist with snakes.
Still have questions about snakes or identifications? Feel free to email the herpetology staff at the Florida Museum with your questions or feedback on this profile.