Northern Cottonmouth
Agkistrodon piscivorus • Order: Squamata, Suborder: Serpentes, Family: Viperidae, Subfamily: Crotalinae, Genus: Agkistrodon, Species: Agkistrodon piscivorus
Southeastern United States, ranging from Virginia south to Florida and west to eastern Texas and Oklahoma, including the Mississippi River Valley north to southern Illinois.
Look up Northern Cottonmouth in the Snake Encyclopedia →Venomous Status
Venomous (Solenoglyphous fang type)
Danger Level
High Risk; while rarely fatal with modern medical treatment, they are capable of delivering significant envenomation leading to severe tissue damage or limb loss.
Family
Order: Squamata, Suborder: Serpentes, Family: Viperidae, Subfamily: Crotalinae, Genus: Agkistrodon, Species: Agkistrodon piscivorus
Conservation
Least Concern (IUCN); widespread and stable, though local populations are threatened by habitat loss and persecution.
Physical Description
Large, heavy-bodied snake. Typically dark brown, olive, or black (often darkening with age until patterns are nearly obscured). Broad, spade-shaped head with a dark 'mask' stripe through the eye. Vertical pupils. Strongly keeled scales.
Size & Dimensions
The specimen appears to be an adult. Typical adult range is 30 to 48 inches (76–122 cm), with a maximum record of approximately 74 inches (188 cm).
Habitat
Semi-aquatic species found in swamps, marshes, slow-moving streams, lakes, and retention ponds. Often seen basking on logs or rocks near water; also found in terrestrial areas adjacent to wetlands.
Behavior & Temperament
Known for a defensive display involving opening the mouth to reveal a white 'cotton' interior. Generally nocturnal but frequently basks during the day. Defensive when provoked but usually prefers to retreat.
Diet & Feeding
Generalist carnivore; hunts fish, amphibians, lizards, other snakes, birds, and small mammals. Uses both ambush and active foraging strategies.
Reproduction
Ovoviviparous (gives birth to live young). Litters typically range from 1 to 20 neonates, born between August and October. Young possess bright sulfur-yellow tail tips.
Venom Profile
Predominantly hemotoxic (contains enzymes like metalloproteinases) causing tissue destruction, swelling, and systemic coagulopathy.
Look-alikes
Commonly confused with non-venomous Water Snakes (Nerodia spp.). Nerodia have round pupils, lack heat-sensing pits, and have narrower heads. Also similar to the Copperhead (Agkistrodon contortrix) which has lighter coloration and hourglass patterns.
Conservation Status
Least Concern (IUCN); widespread and stable, though local populations are threatened by habitat loss and persecution.
Cultural Significance
Often the subject of urban legends regarding aggression or 'falling into boats.' It plays a vital role in balancing wetland ecosystems by controlling rodent and amphibian populations.
Notable Features
The 'cottonmouth' gape threat display and the presence of loreal pits (heat-sensing organs) located between the nostrils and eyes.