Nerodia (water snakes)

Water snakes are the most common snakes encountered on field trips.  Being able to identify these snakes is critical in this course. The following presentation will show you characteristics of Nerodia and different species of Nerodia that you will likey seen in the course.

Handling of venomous or dangerous animals will result in a severe academic penalty.

Snakes of the genus Nerodia are typically large snakes that are found in or around water. Large adults are around 3 to 4 feet in length.  Nerodia has very uniquely shaped scales on their lips, the upper labials (1) scales and the lower labials (2) make the snake look like as if it was smiling. Compared to other snakes, the head of a Nerodia, just looks totally different.
 
Nerodia's scales are always keeled. Meaning the that there is a rise in the middle of an individual scale. This makes the body of the snake feel rough. Keeled scales do not reflect light as well as smooth scales, therefore the snake has a dull appearance.  The snake on the left is the Nerodia rhombifer and the snake on the right is Nerodia erythrogaster transversa. Notice the scale pits on both snakes.
 
The anal plate (belly plate that covers the anus) is always divided on Nerodia.  The scale plate right above the yellow arrow is the anal plate. It can either be single or divided. The scales below the yellow arrow are subcaudal scales. Non-venonmous snakes all have divided subcaudal plates. Just based on these two characteristics alone, you can rule out a lot of other species of snakes.
 
 
Nerodia have many different ways of defense. If you held on to a rhombifer, you would get bitten and/or get musked by discharged musky fluid/feces. The second thing you will notice is that the snake will change the shape of its head. They mimic pit vipers by using their jaw bones to make their head more trianglar, in hopes that you will mistakenly identify it as a venomous snake and leave it alone.
 
Nerodia are mistaken for the venomous Cottonmouth (Agkistrodon piscivorus)all the time.  Based on head shape alone, Nerodia looks nothing like a Cottonmouth. Nerodia shares the same habitat as cottonmouths and even eats the same type of foods as cottonmouths. Nerodia also does not have facial pits, Pit vipers such as Cottonmouths, Copperheads and Rattlesnakes do.
 
At night, you will find Nerodia hunting fish and frogs in creeks. Adult Nerodia will eat anything. If a inch long cricket frog jumps close to its mouth, it will snap it up like a piece of popcorn.