Arboreal adaptations of snakes.

To start with, I will show you pictures of snakes that occupy different ecosystems and you will probably instantly notice some differences between them. Those differences cover not only the appearance of the snakes but also their behaviour and foraging strategies.

Morelia viridis - Arboreal green tree python

http://www.reptilesmagazine.com/Care-Sheets/Snakes/Green-Tree-Python/

Cerastes Cerastes - Ground/burrowing  horned desert viper

http://rivista-cdn.reptilesmagazine.com/Hornviper_Cerastes_cerastes.jpg?ver=1385057346

Laticauda colubrina -  Sea living banded sea krait

http://www.arkive.org/banded-sea-krait/laticauda-colubrina/image-G125624.html

As you can see they are pretty different. What causes this variation? The answer is simple: Evolution! Those differences are adaptations to particular ecosystems. Snakes that occupy same or similar habitat will share some of the adaptations, for example, cryptic skin pattern of snakes' that hide between fallen leaves on the forest's ground.

But what about arboreal snakes? Does arboreal snakes share some similarities? 

Amazon tree boa (Corallus hortulanus)

http://www.sciencephoto.com/media/379847/view

Asian vine snake (Ahaetulla prasina)

http://www.arkive.org/

Green pit viper (Trimeresurus albolabris)

http://commons.wikimedia.org/

These snakes represent three different taxa, so they aren't closely related to each other. Amazon tree boa represent Boidae and lives in South America, Asian vine snake is Colubrid snake from
South-East Asia as well as Green pit viper which, as name shows, represent Vipers. All of those snakes spent majority of their lives on trees and their branches.  There are a lot of shared adaptations which are common in arboreal snakes and rarely seen in snakes occupying different ecological niches. The arboreal specialization is  characteristic for tropical climate.

But what exactly 'Arboreal' means?

'Arboreal' (latin arbor - tree) means: Living in or among trees.
Putting this in more comprehensive answer, arboreality is a trait showing consistent association with trees. This trait is adaptive to some aspects of environmental and ecological conditions.

Arboreal snakes have several body modifications that help them survive and be successful predator in the tree canopy.

• They have characteristic mid body lateral flatness, more broadly said, they are more slender and flatter than other non-arboreal snakes.

• Longer tail length in relation to body length and tail prehensility (which means an organ adapted to holding or grasping)

• Smaller sizes of clutches. The slender body might predestine those snakes to have smaller clutch size. This gives possibility for mothers not to have a handicap since they live on the trees. 

• Shift in the position of ovaries. This ovarian asymmetry gives them ability to minimize body distention during pregnancy period. Lack of strong distention keeps them slender even while keeping big follicles.

• Ontogenetic color changes and polimorphism. It enables snakes' to live in different ecological niches (for example in different height of the trees).

• High aggression (decreases with age). It is defending mechanism for youths and an excellent feeding response that helps them survive in natural environment and to thrive in captivity.

• Bigger heads in relativity to body length and generally, strong, heart-shaped heads. This distinctive shape is a result of presence of strong jaw muscles to prevent their prey from escape. 

• Longer teeth. Arboreal snakes have one of the longest teeth in snake's world. For example Emerald tree python and Green tree python can reach teeth size of 3-4 cm that is close to length of Gabon viper fangs (longest snake-world fangs)!

This is a head of Emerald tree boa that I have dissected a year ago. You can see there a pretty devastating teeth (and yes! during preparation my gloves were pierced all the time).

• My research suggests that constricting snakes like pythons and boas have lengthen nasal complex in relativity to other snakes, that probably allows them more precise grasp of the agile prey. You can see this long nasal complex on the picture above. 

• Good vision. We can even assume that the best from all snakes: from excellent binocular vision of vine snakes to special light reflecting layer of tapetum lucidum in tree boas (that's why one of the easiest ways of searching for those snakes is with flashlight). Good vision helps them localize prey and be more accurate during striking.

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhNcAcV-lGQltiURD6sRGW8rrTgwAKwBmMvHbXgF-A57jeKwF5PsMvxPrIjRvFqpH56duy1Z5CWhFoLS-GanZs4QMzukCs-XI9_2lPSK4V0SEaH3YtYnvCkwHeA5a_PidmLrdb_SalURkca/s1600/Tree+boa.JPG

•  Arboreal snakes have almost no possibility for precise thermoregulation. There is a small amount of sunlight that pierce trough dense tree canopy and all sunny locations are unpopular, probably because of the risk of predation. As a result of living in this environment they have lower body temperature than other snakes. Additionally, the arboreal nocturnal snakes have lower body temperature than diurnal arboreal snakes (which is quite obvious).

The ultimate adaptation to living on tress is diving, or air sliding, or more popularly called - flying.

The South-East Asian Chrysoplea taxa, known as paradise snakes, posseses the ability to move from one tree to another trough gliding in the air. This is really amazing and in few words it is achieved by basically further flattening the body. 

Here is a short video from National Geographic where you can see this amazing ability.

Arboreal snakes are highly adapted to their environment and they are undoubtedly successful predators. Those interesting snakes in a variety of ways are 'marvelous monsters' of the natural world and as a pet snake they can give an opportunity to observe interesting behaviours and admire unique colors and patterns. The only disadvantages with those snakes are high price and demand of specific conditions to keep (and breed) them with success.

I think this post is already longer that I've expected, so if you'll still have any questions, do not hesitate to ask in comments section  and I will try my best to answer them.

Cheerio!