Cottonmouth Basics

Adult cottonmouth snakes are large and capable of delivering a painful and potentially fatal bite. When threatened, they may respond by coiling their bodies and displaying their fangs. Although their aggression has been exaggerated, individuals may bite when feeling threatened or being handled. This is the world’s only semi-aquatic viper, usually found in or near water, particularly in slow-moving and shallow lakes, streams, and marshes. The snake is a strong swimmer and has even been seen swimming in the ocean. However, it is not fully marine, unlike true sea snakes. It has successfully colonized islands off both the Atlantic and Gulf coasts.

This is the largest species of the genus Agkistrodon. Adults commonly exceed 80 cm (31 in) in length; females are typically smaller than males. This is the most aquatic species of the genus Agkistrodon, and is usually associated with bodies of water, such as creeks, streams, marshes, swamps, and the shores of ponds and lakes.

Are Cottonmouth Snakes Dangerous?

The aggressiveness of these snakes has been greatly exaggerated. In tests designed to measure the various behavioral responses by wild specimens to encounters with people, 23 of 45 (51%) tried to escape, while 28 of 36 (78%) resorted to threat displays and other defensive tactics. Only when they were picked up with a mechanical hand were they likely to bite. This species may be active during the day and at night. However, on bright, sunny days, they are usually found coiled or stretched out somewhere in the shade. In the morning and on cool days, they can often be seen basking in the sunlight.

Its diet includes mammals, birds, amphibians, fish, snakes, small turtles, and small alligators. Cannibalism has also been reported. Normally, though, the bulk of its diet consists of fish and frogs. They are opportunistic feeders and sometimes eat carrion, making them one of the few snakes to do so. 

Below is a great image posted on Instagram, taken of a Cottonmouth in the Florida swamps.

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One of my 2018 most popular photos was this cottonmouth shot I took out in the Everglades. Cottonmouths get their name from this threat display of gaping their mouth to show the “cotton” white inside, which will definitely get your attention in a generally drab brown and green environment. Cottonmouths can be very defensive and some readily strike when threatened, but they are NOT aggressive and don’t chase people. Cottonmouths are famous for being "aggressive" but after handling them since I was a child and seeing literally thousands I have never seen one act aggressive or chase as people often claim. They can definitely be very defensive and stand their ground, some will readily strike, but they do not pursue people or act aggressive. One of the most common ways people are "chased" by a snake or alligator or many other animals is when they are between that animal and its safe place, such as if you get between a cottonmouth and the water. It will come right at you to try to get to the water behind you because that's where it wants to hide away from you. It is not coming to you it's trying to get away from you by going to the safe place but you happen to be in the way. Word of advice, don't be between an animal and it's safe place! Photographed with a Canon 80D, 10-17 fisheye lens. If you enjoy my photos I always read and appreciate comments, also feel free to share and see more at my website www.ChrisGillette.com #aquaticadigital #underwaterphotography #uwphotography #florida #therealflorida #everglades #swamp #wetland #southflorida

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