Meet The Cottonmouth Snake

This is the next in a series on snakes that’s being written for you by The Houston Zoo’s Herpetology Department Supervisor, Judith Bryja. Our Herp Department knows their stuff, and since we get so much interest in snakes, Judith is writing this informative blog series each week just for you!  If you’d like to read the series from the beginning, click here.

Our featured snake for this week is the water moccasin a.k.a. the cottonmouth. 

This is the most notorious venomous snake in this area. They are venomous pitvipers just like copperheads and rattlesnakes.  They are variable in color and pattern and many other species of snake are mistaken for them.  Black, brown, or olive with or without markings describe this snake.  Babies have distinct markings (and a bright yellow tail tip just like the copperhead) but these fade with age so that some old animals don’t show any pattern at all. 

Western cottonmouth (Agkistrodon piscivorus leucostoma)


These are stout bodied snakes; the body is thick and they have short tails (the body hardly tapers and then all of a sudden there’s the tail).  The belly is dark brown or black.  Usually visible is a dark cheek stripe.  And we can’t leave out the reason for the moniker of cottonmouth.  The inside of the mouth is white and they don’t hesitate to show it to you when you come across one. 

Average adult size of this snake is 24-36 inches despite the stories you’ve probably heard.  The biggest one ever recorded was right about 5 feet. 

Cottonmouths can be found near just about any kind of aquatic habitat such as swamps, marshes, and streams.  When swimming, much of the body is visible above the water line and the head is held up high.  They are opportunistic and not super picky eaters.  The bulk of their diet is frogs, fish, and salamanders though they are also known to take mammals and birds.  Mating takes place in the spring and live babies are born in the fall.   

A very light uniformly colored cottonmouth (Agkistrodon piscivorus leucostoma)

If they have a convenient escape route when approached, these snakes will usually take it.  If not however, these guys get quite intimidating.  They will look up at you and strike a pose as in the first photo in this blog, the tail is twitched back and forth like a cat or rapidly vibrated against the ground, and the mouth is held wide open showing off the brilliant white interior.  They are also happy to strike if you get too close.   A western cottonmouth can be seen on display in the Reptile/Amphibian building.

Juvenile cottonmouth (Agkistrodon piscivorus leucostoma)

 Are you coming back for another installment in this cool Snake Series? Yep, we hope you are!

For more information on Texassnakes, Judith has reccomended these two resources: and  The Field Guide to TX Snakes written by James Dixon and former Houston Zoo director John Werler.

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