Python, Green Tree

Scientific Name: Morelia viridis

Fast Fact:

The green tree python’s amazing similarities to the emerald tree boa are an example of convergent evolution.  Although these snakes look virtually the same and share similar habitats, they live in completely different parts of the world and are, in fact, from different snake families.

Green Tree Python (Photo by Charlie Morley)

STATUS: Despite some threats to local populations due to harvesting for pet trade, the green tree python is listed as Least Concern by the International Union for Conservation of Nature.  Their bright yellow, red and green colors make these snakes very popular as household pets. 

HABITAT:  The green tree python is found in the lowland tropical rainforests of Australia and New Guinea.  As the most arboreal python species, these snakes spend the majority of their time up in the trees.  The young tend to live mostly on the edges of forests or in forest gaps, whereas the adults live under closed canopies. 

DIET: A typical meal for a green tree python depends somewhat on the snake’s age.  Small hatchlings tend to go after invertebrates, an easy prey.  As they become juveniles, they will hunt small animals, such as lizards.  Adult green tree pythons will eat all of the above, along with small mammals and birds.   These snakes have very efficient digestive systems, enabling them to go long periods without eating.  They spend a significant amount of time in the same position.  Their resting posture is coiled up, hanging on a tree branch or vine.  When they are ready to eat, these ambush predators will stay in one place on a tree for days at a time, waiting for prey to pass by.  The difference is in their posture; in their hunting posture, they keep their tail end wrapped firmly around a tree while the head extends out, ready to strike.  Occasionally they have been known to use caudal luring, in which they use the tip of their tail to lure their prey towards them.  Once they catch their prey, they will constrict it until it expires.  Green tree pythons typically only change their position at dusk or dawn in an effort to avoid being noticed. 

PHYSICAL CHARACTERISTICS: Green tree pythons can grow to be about six feet long.  Adults have a bright green body.  On the dorsal side they have a ridge of white or yellow scales down the length of their body, and on the ventral side they have yellow scales.  Young green tree pythons are actually bright yellow or brick red.  On their dorsal side they have white blotches with dark brown or black outlines.  They also have a white streak that goes from their nostril, through their eye, to the back of their head.  All green tree pythons have small, irregular scales on their heads and prehensile tails to help them climb.  They also have labial pits in the scales of their upper lip.  

Ontogenetic Color Change

Ontogenetic color change refers to the way an animal changes colors during its lifetime.  The different color stages of the green tree python seem to provide the right camouflage for their surroundings at each stage of life.  Young green tree pythons are yellow or red which helps them blend better against the trees and leaf litter at the forest edges, where they typically reside.  These areas tend to be home to smaller prey, making it easy enough for the young pythons to find food.  The green coloring of the adults helps them to blend in well in the darker, closed-canopy parts of the forest where all of the surroundings are lush and green.  This part of the forest contains larger prey, perfect for a larger snake.  The green tree python’s camouflage also helps protect it from the eyes of predators in the forest.

When it is time for young green tree pythons to change colors, they can do so overnight or it could take several months.  The red juveniles take a longer amount of time to turn green because they must first change to yellow.  The color change generally occurs in several patches of skin at a time.  Even when a snake becomes fully green, it has not necessarily reached sexual maturity.  Often that process can take several years and will be complete long after the color change.

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