Only one kind of cottonmouth is found in Texas. It is one of our heaviest and largest poisonous snakes and may reach a length of more than five feet. When viewed from above, the head appears triangular shaped and from the side the head looks flat on top.

The eye pupils, as with all members of the pit viper sub-family, are elliptical.

WESTERN COTTONMOUTH
Agkistrodon piscivorus leucostoma

Description—This is the most variable poisonous snake in the state, both in color and in the presence or absence of markings. Adults are much less brilliantly marked than are the young or newborn snakes. Adults have a background of dark brown and are marked by from 10 to 15 dark, wide crossbands somewhat lighter in the center than at the edges. The bands, which have irregular edges, become a little wider along the sides. However, not all cottonmouths look like this. While some individuals have clearly defined crossbands, others have none. There is also considerable variation in color. Some cottonmouths are brown; some are olive brown or olive green; and some are entirely black. The lower jaw, as well as the upper jaw below the eye, is light in contrast to the dark color on top of the head. Young cottonmouths are vividly marked on a background of reddish-brown, highlighted by darker brown bands edged with white. They look much like copperheads.

Size—In Texas, this heavy-bodied snake reaches a maximum length of about four and a half or five feet, but the average is more nearly three feet.

Young—About eight are born in each litter. They are from six to eight inches long at birth.

Distribution—The cottonmouth has been reported in the following counties: Anderson, Aransas, Atascosa, Austin, Bandera, Bexar, Bowie, Brazos, Brazoria, Burleson, Burnet, Cass, Calhoun, Chambers, Cherokee, Collin, Colorado, Comal, Dallas, Denton, Ellis, Falls, Fannin, Fisher, Fort Bend, Galveston, Goliad, Gonzales, Grayson, Guadalupe, Hardin, Harris, Harrison, Hays, Henderson, Houston, Jasper, Jefferson, Kaufman, Kerr, Kimble, Lamar, Leon, Liberty, Limestone, Marion, Mason, Matagorda, Maverick, McLennan, Medina, Montgomery, Morris, Nacogdoches, Newton, Nueces, Orange, Parker, Polk, Red River, Refugio, Robertson, San Jacinto, San Patricio, Shelby, Smith, Sterling, Tarrant, Tom Green, Travis, Uvalde, Val Verde, Victoria, Walker, Wharton, Wilson, and Wise.

The cottonmouth is one of our largest poisonous snakes. It is particularly abundant in the coastal marshes of southeastern Texas where it is found along streams, ponds and lakes. Although ordinarily rather sluggish, it immediately draws back its head and opens its mouth widely in a threatening manner when annoyed, exposing the white tissue lining the inside of the mouth. This characteristic pose is responsible for its popular name. Moreover, like the copperhead, which also lacks rattles, it has the habit of vibrating its tail when sufficiently annoyed. Thus, when it is among dry leaves, or if the tail strikes a hard object, the resulting sound may be similar to that made by a rattlesnake.

The name water moccasin, which is loosely applied to any and all water snakes as well as to the cottonmouth, has resulted in a popular but misplaced belief that all “water” snakes are poisonous. It should be pointed out here that the cottonmouth, Agkistrodon piscivorus leucostoma, is our only poisonous aquatic serpent. The several kinds of harmless water snakes, which in some instances resemble it, are devoid of poison. They can, at most, inflict a bite no more serious than the scratch of a cat and these wounds require only the first aid recommended for minor cuts.

Harmless water snakes most frequently mistaken for the cottonmouth include the large diamondbacked water snake of central and eastern Texas, the blotched water snake found over most of the state, and the yellowbellied and broadbanded water snakes of eastern Texas. Most of them are relatively heavy bodied, possess somewhat diamond shaped heads and, although not venomous, will bite viciously if stepped upon or handled.