Harmless Watersnake or Venomous Water Moccasin?
There are many harmless watersnakes (Nerodia species) that are frequently confused with venomous Water Moccasins (Agkistrodon piscivorus, a pit viper). Sadly, these harmless snakes are often killed by people who simply fear for the safety of their family and pets. Both watersnakes and Water Moccasins are dark, rough-looking snakes found near water, along the edges of canals, ponds, and lakes. Both of them may have "facial bands" -- dark stripes that run from the eye back to the corner of the jaw. Venomous Water Moccasins have heat-sensing pits between the eye and nostril (watersnakes don't), and have vertical eye pupils (watersnakes have round pupils), but these are hard to see from a safe distance. Most people, even those who do not fear snakes, would feel safer if they were able to identify snakes near water as harmless or venomous. So how can you tell them apart?
There are a few key characteristics that you can use
to tell watersnakes and Water Moccasins apart:
CAUTION! -- With practice, you can learn to tell the difference between watersnakes and Water Moccasins. However, if you are not absolutely sure that the snake is non-venomous, give it space! In fact, since even harmless watersnakes can bite, the best policy for dealing with snakes is to simply "leave them be" to play their important roles in our native ecosystems.
BODY SIZE
Venomous Water Moccasins have bodies that are
VERY thick and heavy for their length.
The body of this young adult Water Moccasin is very
thick for its length (and the head is blocky).
Older adults are often much darker -- almost solid black.
(Photo taken after snake was needlessly killed for ID purposes)
Harmless watersnakes have bodies that are
more slender for their length.
This Florida Green Watersnake has a slender body (and narrow head).
Compare the body of this Banded Watersnake to that
of the Water Moccasin --
much more slender for its length.
BUT -- harmless watersnakes often flatten their
bodies (and heads)
when they feel threatened, making themselves look much larger.
For its length, the body of this snake is still more slender
than a moccasin.
HEAD AND NECK SIZE AND SHAPE
Venomous Water Moccasins have large, blocky heads and distinct necks.
Notice the wide, blocky head of this adult Water
Moccasin.
(Photo taken after snake was needlessly killed for ID purposes)
Notice the wide head and very obvious neck on this
juvenile Water Moccasin.
(Photo taken after snake was needlessly killed for ID purposes)
Harmless watersnakes have heads that are
more narrow, without distinct necks.
Notice the slender, elongate head of this Banded Watersnake.
Notice that this Banded Watersnake has no distinct
neck.
(Photo taken after snake was needlessly killed for ID purposes)
Harmless watersnakes often flatten their heads
when they feel threatened, making the head look triangular.
Notice that the head of this Banded Watersnake looks
flattened -- not blocky, and there is no distinct neck.