Eastern Cottonmouth, Cottonmouth Moccasin, Water Moccasin, Moccasin



Scientific name: Agkistrodon piscivorus piscivorus (LACÉPÈDE 1789)
* Currently accepted name

* scientific names used through time

  • Crotalus piscivorus – LACÉPÈDE 1789
  • Trigonocephalus piscivorus – DUMÉRIL & BIBRON 1854
  • Ancistrodon piscivorus – COPE 1860
  • Toxicophis piscivorus – BAIRD & GIRARD 1853
  • Agkistrodon piscivorus piscivorus – CONANT & COLLINS 1991

Description: Average adult size is 20-48 inches (51-121 cm), record is 74.5 inches (189 cm). A dark-colored, heavy-bodied snake. Juveniles are brightly colored with reddish-brown crossbands on a brown groundcolor. The dark crossbands contain many dark spots and speckles. The pattern darkens with age so adults retain only a hint of the former banding or are a uniform black. The scales are keeled. The eye is camouflaged by a broad, dark, facial stripe. The tip of the snout has two vertical dark lines. The head is thick and distinctly broader than the neck, and when viewed from above, the eyes cannot be seen. The top of head in front of the eyes is covered with large plate-like scales. The pupil is vertical (catlike). There is a deep facial pit between the nostril and the eye. Young juvenile cottonmouths have a sulfur-colored tail.



A. Top of the head (notice the large plate-like scales on the top of the head, and that the eyes cannot be seen from above)
B. Underside of the head (chin and throat)
C. Front (face view) of the head
E. Keeled Scales

Range: Found the extreme western panhandle of Florida. Outside of Florida it is found to the north and east through Alabama to central Georgia and Virginia

Habitat: Cottonmouths can be found along streams, springs, rivers, lakes, ponds, marshes, swamps, sloughs, reservoirs, retention pools, canals, and roadside ditches. It occasionally is found far from water


Comments: VENOMOUS: Cottonmouth bites can be quite dangerous. The victim should seek immediate medical care from a physician or hospital experienced in treating snakebite.

When threatened, the cottonmouth may respond by coiling its body and opening its mouth as though ready to bite — see photograph in Florida cottonmouth, Agkistrodon piscivorus conanti. The exposed white interior of the mouth is what gave rise to the common name, 'cottonmouth.' Given the chance, the cottonmouth usually will retreat. This open mouth threat display has led to the widespread belief that cottonmouths are aggressive snakes.

Some people believe cottonmouths lie in wait on tree limbs overhanging water so they can drop into boats. These are usually cases of mistaken identity. The harmless brown watersnake often basks on tree limbs over the water, and when frightened by a rapidly approaching boat, they will escape by throwing themselves off the limb and into the water. Occasionally the watersnake's attempt to flee comes too late and it falls not into the water, but into the boat. Cottonmouths feed on fish, frogs, mice, rats, and other small mammals. Juvenile cottonmouths have a bright, sulfur-colored tail which they hold erect and wiggle like a caterpillar to attract prey within striking range.

Comparison with other species: Though the Cottonmouth occurs throughout Florida, it is not as abundant as the many species of harmless watersnakes that occur in much the same habitats. Many Florida residents do not even realize that watersnakes exist. As a consequence, every large dark-colored snake found near water is counted, and usually killed, as a Cottonmouth. There really is no excuse for this because Cottonmouths can easily be distinguished from Water Snakes. If the head is viewed from above, the eyes of cottonmouths cannot be seen while the eyes of Water Snakes are visible; Cottonmouths have elliptical pupils and Water Snakes have round pupils; Cottonmouths have a facial pit between the nostril and the eye, and Water Snakes have none. Brightly-colored baby Cottonmouths are sometimes mistaken for the Southern Copperhead (Agkistrodon contortrix), which occurs in Florida only in the panhandle. The two species are easy to distinguish because the dark bars on juvenile cottonmouths have numerous dark spots and speckles in them, while the dark bars on the copperhead have no dark spots or at most only one. In additioin, the eye of the copperhead is not obscured by the dark facial band typical of the cottonmouth.