Northern water snake The belly also varies in color. It can be white, yellow, or gray. Usually it also has reddish or black crescents. The northern water snake is nonvenomous and harmless to humans, but superficially resembles the venomous cottonmouth and is often killed unnecessarily as a result of this mistaken identity. The two can be easily distinguished by morphological traits: the water snake has a longer, more slender body and a flattened head the same width as the neck, round pupils, and no heat-sensing pits. The cottonmouth has a fatter body, a wedge-shaped head with prominent venom glands that are wider than
Venomous snake of snake which are actually poisonous. "Rhabdophis" keelback snakes are both venomous and poisonous - their poisons are stored in nuchal glands and are acquired by sequestering toxins from poisonous toads the snakes eat. Similarly, certain garter snakes from Oregon can retain toxins in their livers from ingesting rough-skinned newts. , mostly on rodents, is a common indicator of snakes' toxicity with a smaller resultant value indicating a higher level of toxicity. There have been numerous studies on snake venom with a variability of potency estimates. There are four methods in which the LD50 test is conducted, which are injections