Environment

Don’t judge a snake by its colour

It’s not easy being a snake in the wild. With dozens of predators, death lurks in every nook. So they must resort to some weird tricks in order to survive. Now, a report in Herpetology Notes describes how an Indian coral snake resorts to mimicry to fool its predators. The tropical snake Calliophis bibroni is a venomous species endemic to the Western Ghats.

In its infant stage, the snake develops a bright red colouration with black stripes, similar to another venomous snake, Sinomicrurus macclellandi.

Other snakes, too, exhibit this type of mimicry, with two or more species sharing the same danger signals.

Juvenile Calliophis bibroni mimics Sinomicrurus macclellandi.

Juvenile Calliophis bibroni mimics Sinomicrurus macclellandi.  

 

Once the predator has learnt that red and black snakes are venomous, it will never touch any other species with the same colour pattern.

But the bright red colour that served as a protective shield of sorts in infancy would be a liability once the snake grows into an adult, as it would scare away its prey as well. To address this, the snake turns fully black in colour as it grows up, merging well with the surroundings. This is the first time such dual mimicry has been reported from India.

Another common type of mimicry is Batesian Mimicry, wherein non-venomous snakes copy the patterns of venomous snakes to fool the predator.

“The wolf snake, a non-venomous snake, has white stripes on its body resembling the venomous krait,” explains Dileep Kumar of the Centre for Venom Informatics, University of Kerala, and the first author of the paper on the coral snake.

Sinomicrurus macclellandi

Sinomicrurus macclellandi  

 

Snakes are capable of using other tactics to distract the predator. “Oligodon snakes or kukri snakes are non-venomous snakes of South Asia. They are capable of twisting their tail and displaying their bright ventral side to distract the predator and save their head. Display of bright colours, or aposematism, is seen in many other species, including frogs and lizards. Some lizards have bright, coloured tails to signal that they are poisonous,” says Dr. Abhijit Das, from the Wildlife Institute of India.

Hissing and opening the jaw to display the colour of the mouth are among the other tactics. “Snakes can also puff up their throat when agitated. Some snakes are known to display a different, bright colour skin under their scales when disturbed,” points out Ajay Kartik, assistant curator at the Madras Crocodile Bank.


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Printable version | Dec 2, 2021 3:12:01 AM | https://www.thehindu.com/sci-tech/energy-and-environment/dont-judge-a-snake-by-its-colour/article22492389.ece

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