Water moccasin : A venomous North American snake (Ancistrodon piscivorus) allied to the rattlesnake but destitute of a rattle. It lives in or about pools and ponds, and feeds largely of fishes. Called also water snake, water adder, water viper.

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Taxonomy
snakes, Agkistrodon piscivorus, species, piscivorus, specimens, venom, Conant, cottonmouth, tail, Ancistrodon piscivorus, moccasin, reptiles, fish, water moccasin, plates, North American, bites, Gloyd.

Defination from the web:
water, swamp or black 'moccasin', 'viper', 'cottonmouth.[2] Many of the common names refer ... The king snake (Ophibolus sayi) sups on a full grown water moccasin (Ancistrodon piscivorus). Amer. Nat., 15: 561-562. Jan G. 1863. ...