Corallus caninus is a non-venomous boa species found in the rainforests of South America. No subspecies are currently recognized.
Adults grow to about 6 feet (1.8 m) in length. They have highly developed front teeth that are likely proportionately larger than those of any other non-venomous snake.
The color pattern typically consists of an emerald green ground color with a white irregular interrupted zigzag stripe or so-called 'lightning bolts' down the back and a yellow belly. The bright coloration and markings are very distinctive among South American snakes. Juveniles vary in color between various shades of light and dark orange or brick-red before ontogenetic coloration sets in and the animals turn emerald green (after 9–12 months of age). This also occurs in Morelia viridis, a species in which hatchlings and juveniles may also be canary yellow or brick-red. As opposed to popular belief, yellow juveniles (as in the green tree python) do not occur in the emerald tree boa.
Based on locality, enough that some herpetologists have considered whether they should be classified as a new subspecies. The name recently suggested for this morphological variant, but not yet widely accepted, is Corallus batesii. Specimens from the Amazon River basin tend to grow the largest, are much more docile than their Northern relatives and attain lengths of 7–9 feet (2.1–2.7 m), while the overall average size is closer to 6 feet (1.8 m). Those from the southern end of their range in Peru tend to be darker in color. Amazon Basin specimens generally have an uninterrupted white dorsal line, whereas the white markings in the Northern Shield specimens are quite variable. The snout scales in Amazon Basin specimens are also much smaller than in their Northern, Southern and Western counterparts found, for example, in Surinam, Venezuela, Bolivia,and French Guiana. Hybrid forms between the Northern Shield Corallus caninus and the Amazon Basin form are also known to exist.
C. caninus appears very similar to the green tree python, Morelia viridis, from southeast Asia and Australia. Only very distantly related, this is an example of convergent evolution. Physical differences include the head scalation and the location of the heat pits around the mouth.
