The Bluntheaded Snake: the ultimate lizard predator

One of the most strikingly specialized reptiles making its home in Drake Bay’s rainforest is

Bluntheaded Snake – Imantodes cenchoa

the Common Bluntheaded Snake, Imantodes cenchoa. These common nocturnal snakes are unlikely to be confused with any other snake in the area besides their close relatives: the rarely seen Banded Bluntheaded Snake (Imantodes gemnistratus) and the equally rare Speckled Bluntheaded Snake (Imantodes inornatus). Their slender, streamlined body sets these snakes apart from most other snakes and is crucial in capturing their favorite meals: sleeping lizards.

Bluntheaded SnakeIn Costa Rica, most lizards are diurnal and usually sleep through the night. Due to the countless threats faced by these creatures once darkness shrouds the forest, lizards have developed an ingenious survival strategy.

When choosing a perch to pass the night, most lizards wisely seek out the mid-line of a leaf or a very delicate branch or vine. This way, if they feel the movement of something moving up the plant to eat them sometime during the night, they can simply drop to the ground and make a quick escape from danger. Generally, this is a really good strategy, but the Bluntheaded Snake’s highly specialized skeletal structure helps them surpass it.

The Bluntheaded Snake’s skeletal structure is not unlike the structure of an I-beam. In cross section, the snake’s body is more reminiscent of a triangle than the more common tubular shape of most other snakes. This, along with interlocking vertebrae and reinforcing back scales, allows Bluntheaded Snakes to stretch more than half of their body into mid-air and snatch the unsuspecting lizards from their perch without ever touching the plant. A very long, prehensile, tail has the strength to support all of the Bluntheaded Snake’s body weight, giving them an extra advantage when hunting from above. Also, the snake has massive

Bluntheaded Snake feeding on an Anole Lizard

eyes which it can actually cast downward, providing Bluntheaded Snakes an effortless, inconspicuous view from above. All things considered, the poor lizards have little chance against such a formidable predator. The moral of the story: in the rainforest every good strategy has an even better counter-strategy.

Bluntheaded Snakes are rear-fanged snakes which are used to inject a mild venom. Once

they have secured their prey, their venom will immobilize it before they begin feeding. They can take prey up to ten times the size of their very narrow neck and adult snakes can easily feed on juvenile Green Iguanas and Basilisks. Despite being mildly venomous, Bluntheaded Snakes are docile and gentle creatures.

They do not bite as a defensive reaction and are easily handled. An encounter with a Bluntheaded Snake is always very special indeed. It gives our guests on the Night Tour the chance to handle these magnificent creatures, dispelling the ingrained fear of snakes held by many and replacing it with admiration and respect for a creature that has evolved to dominate its niche.

Posted by Gianfranco

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