Genus Nerodia

Genus Nerodia is a clade of non-venomous watersnakes ranging throughout North America. Of the ten recognized species spread across the eastern half of the continent,  five are native to and present within the Floridian peninsula. Though entirely non-venomous and non-aggressive, Nerodia watersnakes are often confused with the quite-venomous (but also non-aggressive) Florida cottonmouth, Agkistrodon conanti.

This page provides brief profile descriptions of each of Florida’s Nerodia species, illustrated with photographic galleries of images currently published on this website. Note that these galleries will perpetually update as new content continues to be added to the Floridensis blogroll. For comparison, I’ve also included sections on this page for the Florida cottonmouth (even though Cottonmouths are categorically not watersnakes) and other Nerodia species found throughout North America.

At the bottom of this page, you’ll find a list of general recommended resources relevant to watersnakes and cottonmouths. I’ve also included species-specific links within each species profile. As always, I’ll update this page as time moves forward. There’s always more to learn (and add) when it comes to watersnakes and cottonmouths. If you have any questions or concerns, please don’t hesitate to contact me directly. Please note that I am merely a naturalist enthusiast; I am in no way an accredited “expert.”

Florida Peninsula Watersnake Quicklinks:
Banded | Saltmarsh | Banded (x) Saltmarsh | Florida Green | Brown | Redbelly

Non Florida Peninsula Watersnake Quicklinks:
Diamondback | Northern | Mississippi Green | Brazos | Concho

Non Nerodia Content Quicklinks:
Florida Cottonmouth | Resources

This page was last updated on
Friday 10 July 2020
Check out the Floridensis Gallery List

__________________________
Nerodia fasciata
Banded Watersnake

Species Description:
The Banded watersnake is a live-bearing, non-venomous, and semi-aquatic species ranging throughout much of the American southeast. Adults typically average between 22-42 inches in length and are highly variable in coloration and pattern. Many individuals tend to darken substantially with age, though vertical lip bands often remain evident. Pupils are round. Many adults have a banded pattern running from behind the eye to the corner of the jaw. Preferring calm, freshwater habitats such as ponds, lakes, marshes, and streams, Banded watersnakes feed primarily on fish and frogs. When basking, they are quite casual in preference, sometimes basking on shore and other times basking in tree limbs hanging over water. Dorsal scales are keeled. This species is often confused with the venomous Florida cottonmouth, Agkistrodon conanti.

Recognized Subspeciation:
There are currently three subspecies listed in the American southeast and in Florida: N. f. pictiventris, (the Florida banded watersnake ranging throughout the Floridian peninsula), N. f. fasciata (the Southern banded watersnake ranging north of Florida and N. f. confluens (the Broad-banded watersnake roughly ranging west from Louisiana and into Texas). Along coastal areas of central and southern Florida, this species may hybridize with the Salt marsh snake, N. clarkii.

Informational Sources & Images:
View all Floridensis images for N. fasciata.
FMNH: Florida banded watersnake.
FMNH: Southern banded watersnake.
○ iNaturalist: N. fasciata.

Nerodia fasciata gallery:


__________________________
Nerodia clarkii
Saltmarsh Snake

Species Description:
The Saltmarsh snake is a live-bearing, non-venomous, and semi-aquatic species ranging throughout much of the Gulf states’ coastal and saltmarsh habitats, from Texas eastward to and around the Florida peninsula. Adults typically average between 15-24 inches in length, occasionally a bit longer, and are highly variable in coloration and pattern. Saltmarsh snakes can be orange/red or black/gray in base tone, and they can be striped, blotched, or solid in coloring and patterning. Again, they are extremely variable in appearance (even within a subspecies ranking). Pupils are round. Preferring salt marshes, tidal mud flats, mangroves, and other brackish/saltwater habitats, Saltmarsh snakes feed primarily on small fish, but they will also east small crustaceans. This species is primarily nocturnal and not prone to basking during the daylight (preferring instead to hide throughout the day). At night, they slink around the shallows to feed and breed. Dorsal scales are keeled. Of note, in some parts of Florida, localized populations of N. clarkii have hybridized with the closely-related species N. fasciata pictiventris, the Florida banded watersnake. This seems to especially be the case with Atlantic salt marsh (N. c. taeniata) populations in my home territory of Volusia county, Florida. See entry below.

Recognized Subspeciation:
N. c. clarkii, the Gulf coast marsh snake.
N. c. compressicauda, the Mangrove salt marsh snake.
N. c. taeniata, the Atlantic salt marsh snake.

Informational Sources & Images:
View all Floridensis images for N. clarkii.
FMNH: Gulf coast salt marsh snake.
FMNH: Mangrove salt marsh snake.
FMNH: Atlantic salt marsh snake.
○ iNaturalist: N. clarkii.

Nerodia clarkii gallery:


__________________________
Nerodia clarkii (x)
Nerodia fasciata

Species Description:
In Florida, hybridization between Nerodia clarkii appears to be fairly common with Nerodia fasciata. This appears to especially be the case with localized populations of Nerodia clarkii taeniata, the Atlantic salt marsh snake, and Nerodia fasciata pictiventris, the Florida banded watersnake, in parts of Volusia and northern Brevard counties. N. clarkii and N. fasciata are sister taxa, meaning they are closely related to one another. Future genetic research may find that these two species, N. fasciata and N. clarkii, are indeed one and the same in terms of speciation, which would make this more of an intergrade issue than a hybridization one (but that’s largely speculative on my end). I have documented hybridization of N. clarkii and N. fasciata in both Volusia and Brevard counties. In Volusia salt marsh habitats, I have also found individuals that appeared largely to be Nerodia fasciata instead of Nerodia clarkii.

Informational Sources & Images:
View all Floridensis images for N. clarkii (x) N. fasciata.
○ iNaturalist: N. clarkii (x) N. fasciata.

Nerodia clarkii (x) fasciata gallery:

__________________________
Nerodia floridana
Florida Green Watersnake

Species Description:
The Florida green watersnake is a robust, live-bearing, non-venomous, and semi-aquatic species ranging throughout parts of the American southeast and most of the Floridian peninsula. Adults typically average between 30-55 inches in length and are mildly variable in coloration (ranging from olive green to chocolate brown). The pupils are round, but the irises can be quite dark. This species features an extra row of sub-ocular scales separating the eyes from the upper-labial lip scales. The Florida green watersnake prefers calm freshwater habitats such as ponds and marshes where it feeds primarily on amphibians and fish. Though it prefers to bask on foliage and debris floating directly on the surface of water, it will also bask on the shoreline at times. When startled, it slinks into the water and disappears. Florida green watersnakes can be quite heavy-set and robust. Though not aggressive, they can be strongly defensive. The scales are keeled. Juveniles feature many dark crossbands that fade with time.

Recognized Subspeciation:
There are no subspecies rankings beneath N. floridana. This species is most closely related to Nerodia cyclopion, the Mississippi green watersnake, which ranges further to the west.

Informational Sources & Images:
View all Floridensis images for N. floridana.
FMNH: the Florida green watersnake.
○ iNaturalist: N. floridana.

Nerodia floridana gallery:


__________________________
Nerodia taxispilota
Brown Watersnake

Species Description:
The Brown watersnake is a live-bearing, non-venomous, robust, and semi-aquatic species ranging throughout much of the American southeast. Adults typically average between 30-60 inches in length and are only mildly variable in coloration and pattern. Though some adult patterns may dull with age, the base pattern usually remains visible. Of note, the head can be wider than its neck; the pupils are round. The Brown watersnake prefers stable freshwater habitats such as streams and cypress creeks where it feeds primarily on fish, especially catfish. It will sometimes also eat frogs. The most arboreal of Florida’s watersnakes, the Brown watersnake often climbs limbs and foliage at or above the shoreline, sometimes basking far above the water’s surface. When startled, the Brown watersnake drops from its perch and falls into the water; it is often confused as being a Florida cottonmouth. This species doesn’t stray too far from the water. Scales are strongly keeled. The Brown watersnake is not aggressive, but it will defend itself if necessary.

Recognized Subspeciation:
There are no subspecies rankings beneath N. taxispilota. The Brown watersnake is closely related to Nerodia rhombifer, the Diamondback watersnake, which ranges further to the west. 

Informational Sources & Images:
View all Floridensis images for N. taxispilota.
FMNH: Brown watersnake.
○ iNaturalist: N. taxispilota.

Nerodia taxispilota gallery:


__________________________
Nerodia erythrogaster
Redbelly Watersnake

Species Description:
The Redbelly watersnake is a live-bearing, non-venomous, modestly-robust, and semi-aquatic species ranging throughout much of the American southeast. Adults typically average between 24-40 inches in length. Though juveniles are banded, adults sport a solid dorsal base tone. The belly is devoid of markings other than the ventral base color (depending on the subspecies). The pupils are round. Preying upon amphibians and the occasional fish, the Redbelly watersnake is fairly adaptable to and tolerant of any number of aquatic habitats. In short, if there’s food in the water, it’ll do. This species is also considered to be the most terrestrial of the southeastern watersnakes. They often move pretty far from open water, moving from one body of water to another, snagging amphibians along the way. The scales are keeled. This species is not aggressive, but it will defend itself if necessary.

Recognized Subspeciation:
There have been many recognized subspecies for Nerodia erythrogaster in the past, but recently these subspecies have been collapsed into one nominate species. Historically, three subspecies have been heavily represented. The Redbelly watersnake, N. e. erythrogaster, is dominant in the American southeast, ranging from north Florida, through Georgia, and up the coastal states to Virginia. N. e. flavigaster, the Yellowbelly watersnake, ranges from Alabama and the western tip of the Florida panhandle westward to Louisiana and Arkansas. Finally, the Blotched watersnake, N. e. transversa, is a mid-western subspecies than ranges from Texas and Oklahoma east into extreme southern Louisiana.

Informational Sources & Images:
View all Floridensis images for N. erythrogaster.
FMNH: Redbelly watersnake.
FMNH: Yellowbelly watersnake.
○ iNaturalist: N. erythrogaster.

Nerodia erythrogaster gallery:


__________________________
Nerodia rhombifer

Diamondback Watersnake

Species Description:
Not a native or known Florida species, the Diamondback watersnake ranges throughout the eastern range of Mexico and much of the southern-central interior of the United States (such as Texas, Oklahoma, Lousiana, Mississippi, Kansas, Missouri, Arkansas, and other adjacent states). N. rhombifer is a fairly large species averaging lengths upwards to four feet. Some individuals can reach lengths upwards to five and a half feet. The species is heavily keeled. Its sister taxa is N. taxispilota, the Brown watersnake, though I personally find the Brown watersnake’s temperament to be far more passive than their western cousins. Though entirely non-aggressive, Diamondback watersnakes can be fairly reactive and assertive in defending themselves.

Recognized N. rhombifer Subspeciation:
N. r. blanchardi, the Blanchardi diamondback watersnake.
N. r. rhombifer, the Northern diamondback watersnake.
N. r. werleri, the Werleri diamondback watersnake.

Informational Sources & Images:
View all Floridensis images for N. rhombifer.
○ iNaturalist: N. rhombifer.

Nerodia rhombifer gallery:


__________________________
Nerodia sipedon
Northern Watersnake

Species Description:
Not a native or known Florida species, the Northern watersnake is a remarkably widespread species throughout much of the eastern United States. Ranging from Oklahoma east to the Carolinas, then up north to Maine and back west to Minnesota, and back south through Kansas and Nebraska, and everywhere in between, this species is fairly well adapted to cold temperatures and climates. Averaging between two to three feet in length, this species is somewhat variable in appearance (especially between subspecies rankings/populations). They are prone to basking on foliage at or over the water’s edge and tend to prey upon small fish and amphibians. Juveniles may focus more on worms, leeches, and insects.

Recognized N. sipedon Subspeciation:
N. s. insularum, the Lake Erie watersnake.
N. s. pleuralis, the Midland watersnake.
N. s. sipedon, the Northern watersnake.
N. s. williamengelsi, the Carolina watersnake.

Informational Sources & Images:
View all Floridensis images for N. sipedon.
○ iNaturalist: N. sipedon.

Nerodia sipedon gallery:


__________________________
Nerodia cyclopion
Mississippi Green Watersnake

Species Description:
Not a native or known Florida species, the Mississippi green watersnake ranges from the southeastern Texas east to the tip of the Florida panhandle as well as north through Louisiana, western Mississippi, eastern Arkansas, and western Texas (with limited populations peaking in extreme southeast Missouri, southern Illinois, and western Kentucky. No subspecies are currently recognized.

Informational Sources & Images:
○ iNaturalist: N. cyclopion.


__________________________
Nerodia harteri
Brazos Watersnake

Species Description:
Not a native or known Florida species, the Brazos watersnake is a species limited to the Brazos River system of interior Texas, immediately west from the Dallas/Forth Worth area. No subspecies are currently recognized.

Informational Sources & Images:
○ iNaturalist: N. harteri.


__________________________
Nerodia paucimaculata
Concho Watersnake

Species Description:
Not a native or known Florida species, the Concho watersnake ranges in the Concho and Colorado River systems immediately northwest of Austin, Texas. No subspecies are currently recognized.

Informational Sources & Images:
○ iNaturalist: N. paucimaculata.


__________________________

Agkistrodon conanti

Florida Cottonmouth

Species Description:
The venomous Florida cottonmouth, Agkistrodon conanti, is a frequently-misunderstood venomous species often confused with non-venomous watersnakes of genus Nerodia. Cottonmouths, in short, are not (and are not even closely related) to watersnakes. Ranging throughout the entirety of Florida and parts of southern Georgia, the Florida cottonmouth also sports a wide hybridization zone with the Eastern cottonmouth, Agkistrodon piscivorus (throughout southern Alabama, southern Georgia, and the southern tip of South Carolina). As juveniles, Florida cottonmouths tend to be brightly colored and sport a yellow-tipped tail; this yellow tail fades away as the snake matures, as do the typically-bright brown, gold, and orange dorsal coloring. As adults, Florida cottonmouths are moderately variable in appearance; some individuals can be very dark while others are more coppery. Still, most adult cottonmouths will exhibit banding pattern with a “bullseye” mark (or two) on the side of each dark band. Further, they usually exhibit a dark stripe running along the side of the face and through the eye line.

Differences between Cottonmouths and Watersnakes:
Unlike Neroda watersnakes, Florida cottonmouths do not have pronounced vertical labial (lip) stripes. Also unlike Nerodia watersnakes, Florida cottonmouths have vertical pupils, though in low-light situations the pupils may appear more round than vertical. Similar to Nerodia watersnakes, however, Florida cottonmouths are not entirely aquatic; they can often be found quite far from bodies of water. They are also not overly-prone to climbing and basking over water (unlike the Brown watersnake, which prefers such behavior). Instead, cottonmouths often wait near the edges of water bodies to ambush passing prey (such as mammals, fish, birds, amphibians, and other small reptiles). Finally, the Florida cottonmouth has a strongly-pronounced ridge above each eye. When looking down at a Florida cottonmouth, that ridge will obscure the eyes. In Nerodia watersnakes, the eyes are usually still visible from above.

A Note on Aggression and Defense:
Despite popular opinion based on folkloric stories and misinterpreted events, Florida cottonmouths simply are not aggressive. Though cottonmouths will sometime “stand its ground” and flash its white, cottony inner-mouth as a warning display, most of the cottonmouths I’ve encountered choose instead to retreat to the water and simply swim away. I have had a few encounters where and when cottonmouths actively moved toward me, but that was only because I was standing between the snake and the water. Some might interpret this as “aggression,” but each of these snakes were simply heading for the water. I have never, not once, encountered an aggressive cottonmouth, and I have never seen concrete, documented evidence of aggression in the species. Cottonmouths can be stubborn, sure, and they can also play a strong defensive game, but it would be unfortunate to interpret such behaviors as aggression.

A Metaphor for Energy Conservation in Snakes:
Snakes don’t really have emotions the way people do. They don’t get “pissed off” and seek revenge. Though some cottonmouths may —at first— appear to be “mean,” in reality they’re simply playing the game of life and trying to survive as cost-efficiently as possible. We can think of it this way: In a snake’s reality, energy is the currency of life. In human society, we use money, an imaginary game of currency invented by humans to moderate the exchange of time/labor for goods, right? Well, snakes don’t have money. Further, snakes are cold-blooded organisms, which means energy conservation is critical for survival. In short (and unlike most mammals), a snake wants to get as much energy as it can (through feeding) while burning as little energy as possible (for energy conservation). Thus, like many reptiles, a snake will only burn energy when it feels there is something to gain from it. Most reptiles simply don’t burn energy without some reason or purpose that may benefit it and its survival. Whereas people (and kittens!) may burn extraordinary amounts of energy unnecessarily (a benefit to being a warm-blooded mammal), that’s simply not the reality for reptiles and other cold-blooded organisms. So, think of it this way: What does a cottonmouth have to gain from chasing a person? Chasing a person would inevitably require the snake to burn a lot of energy, right? And what does the snake have to gain from it? A cottonmouth can’t eat a person, so there’s no chance of a paycheck, if you will. Further, by chasing a person, the snake would actively be putting itself in the position for more harm than good. Again, where’s the payoff? Where’s the profit? Where’s the gain? There is none. The idea of snakes being erratically aggressive directly denies the essential logic of a cold-blooded organism’s, such as the Florida cottonmouth, currency of life. Whereas I may burn an extraordinary amount of energy hiking around and photographing these snakes, they  don’t spend tons of energy pushing me back aggressively. They’re more likely to curl up and flex their jaws (which doesn’t require much energy) or beat a retreat into the foliage or the water (which does burn some energy, but also gains the snake the chance to live another day). What they won’t do is add your name to their little black book of revenge and hunt you down. That’s simply not in the energy economics of Florida cottonmouths (or within the limits of their intellectual capabilities, heh). Snakes are, in essence, little machines of the logic and math of energy conservation.

Informational Sources & Images:
○ iNaturalist: A. conanti.

Agkistrodon conanti gallery:

__________________________
RESOURCES

Books & Monographs:

Websites:

Social Media:

__________________________

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s