Worldwide, there are approximately 290 species in the pit viper family,
three occur in Canada:
- northern pacific rattlesnake (Crotalus
viridis oreganus) from south-central
- prairie rattlesnake (Crotalus viridis
viridis) from southeastern Alberta and
- eastern massasauga rattlesnake (Sistrurus
catenatus catenatus) from Ontario.
A second pit viper was once present in
Ontario, the timber rattlesnake (Crotalus horridus). Habitat loss and
human persecution are thought to have caused its extirpation from
Ontario. The last known sighting is from 1941 near Niagara. This species
is now only present in the U.S., where it is in decline.
The eastern massasauga
rattlesnake possesses a long, slender and forked tongue which, when not
extended, is housed within a sheath inside the snake’s mouth. With a
flick of its tongue, the snake gathers information about its
surroundings. Sampling the air allows the snake to retrieve scent
molecules, which it then transfers to its “vomero-nasal organ”
(Jacobson’s organ), located in the roof of its mouth. By interpreting
the information gathered by the nerves within this organ, the snake
learns about its surroundings.