Cottonmouths are vipers built for swamp edges
Agkistrodon piscivorus is North America's standout semiaquatic pit viper—the northern cottonmouth—named for a white mouth flash and a Greek-Latin label that roughly means hook-tooth fish-eater. Adults often top eighty centimetres; one measured one hundred eighty-eight. It haunts creeks and marshes from Virginia to Texas, not dry hills alone.
For decades three subspecies sat under one species name: eastern, western, and Florida cottonmouths. Modern treatments elevate the Florida form to Agkistrodon conanti and keep A. piscivorus as the northern cottonmouth. It is the largest Agkistrodon. Females run smaller than males; adults commonly exceed eighty centimetres, with average study lengths in the mid-range of that size class. Gloyd and Conant recorded a Dismal Swamp specimen at one hundred eighty-eight centimetres. The broad head, blunt snout, and dark facial stripe distinguish adults from copperheads, whose juveniles can look similar until pattern and head bands are compared.
Venom is more toxic than copperhead venom and rich in tissue-destroying cytotoxins. Fatalities are uncommon, yet bites can scar and rarely force amputation. Allen and Swindell compiled mid-century case records from the lower Mississippi and Gulf Coast where encounters are frequent. Brown reported average dried yields around one hundred twenty-five milligrams with a range of eighty to two hundred thirty-seven, plus LD50 figures spanning intravenous, intraperitoneal, and subcutaneous routes. Pain typically exceeds a copperhead bite but falls short of many rattlesnake envenomations; swelling and bruising are common.
Range covers the eastern United States from the Great Dismal Swamp of southeast Virginia through the Florida peninsula west to Arkansas, Oklahoma, and southern Georgia, plus the Ohio River Valley into southern Indiana. Campbell and Lamar list a long roster of states from Alabama to Virginia. Among Agkistrodon it is the most water-tied, favouring streams, marshes, swamps, and lake shores, though it will cross land between wetlands. Juveniles flash a yellow tail tip used as a lure; adults darken until many look nearly black. Semiaquatic life plus potent venom make the cottonmouth a specialist of humid lowlands rather than a generic forest snake.
Source: Agkistrodon piscivorus
