Description

Emerald tree boas are as their name implies a brilliant leaf green colour. The dorsal scales are accentuated by the white diamond-shaped pattern along their vertebral ridge, which is outlined by a darkening of the surrounding green scales . The whites of the scales can also be speckled with black. The ventral colouration ranges from cream to yellow, depending on the individual and its geographic origin. The vibrancy of the green varies depending on its geographic location as does the dorsal pattern ranging from a continuous, unbroken line, through the more common irregular, randomly placed diamond shapes to the almost non-existent accent of white. The intensity of the white colouration usually increases towards the posterior of the snake with the anterior end often quite dull.

They have a comparatively thin neck which supports a large head, having two fairly large bulges on the crown of the head which gives it its characteristic, thick shape.

More prominent female lobes	Less prominent male lobes

This feature is much more prominent in the female of the species and I have found this to be a good indication of the health and fat reserves of the snake, important in the run-up to the breeding season.

One of the most prominent features of the Emeralds head is the pitting that occurs in both the upper and lower labials of the mouth. These pits house the heat-sensitive receptors that play a crucial role in the detection of prey. These pits are clearly visible in the picture below.

The body of the Emerald Tree Boa is laterally compressed and tapers into a strong prehensile tail, which is used to anchor them to a branch, whilst hunting and feeding. Emeralds are the heaviest and longest of the Corallus genus, attaining a body length between five and eight feet.

Due to lack of research, longevity is unknown in the wild but in captivity it is believed that they can easily reach 10 years or over. In my collection I have specimens that have been in captivity over 10 years and are likely to be in excess of 15 years of age, all of which are all still sexually active.

Behaviour

Emerald Tree Boas start to become active at dusk and are hence crepuscular. This is the time when they would perform their normal mobile activities, such as feeding and breeding. Emeralds are highly arborial and spend their day mostly inactive and coiled on a branch in their characteristic resting position.

It has always been assumed that the main part of an Emeralds diet is flying animals such as birds and bats, as they have been known to seize them during mid-flight, constricting and eating them whilst dangling from a branch anchored by their prehensile tail. Although this is certainly still true, more recent studies have uncovered evidence that the Emerald has a greater tendency to forage, and feed on arboreal rodents. Captive evidence suggests that they will come down from their perches and rummage around at ground level and look for prey in this manner.

Being boids, Emeralds are ovoviviparous. This is the production of eggs with a membranous covering and a store of yolk for the embryos' nourishment. These eggs are retained within the females' body during embryonic development and hatch immediately before, during and after they are laid. This gives the impression of live birth, but does not resemble the viviparous reproductive systems of mammals, where a placenta is used to provide the young with nutrients. Between three and thirteen young can be born at one time. Although this amount is generally estimated to be the range, larger numbers have been bred in captivity.

Neonatal Colour Change

At birth, the neonate Emerald Tree Boas are usually red in colour with their white dorsal markings visible. The neonates can also be orange, brown and already green when born. This is known as juvenile polymorphism. Over the next year an ontogenetic colour change occurs, which transforms them from their juvenile colouration to their adolescent green colouration. As the neonate grows and sloughs its skin, the red fades and green blotches appear and spread. At about the age of six months, they take on a golden-yellow appearance that obscures the patterns and colour beneath.

By the time they are eight months old most of the scales have turned a lime green, with just the neck and head remaining mostly red. The original white dorsal markings that the snake was born with remain largely unchanged. By the time they have reached a year old they would have completely changed to green. This green is very much lighter than that of an ageing adult, and the snake continues to get darker as it gets older.