Natures wonders: mock viper changes eye appearance (Introduction)

by David Turell @, Monday, October 10, 2016, 20:35 (1234 days ago) @ David Turell

This snake mimics a real viper as it changes pupil shape. How did it learn to do this?

“'Thailand is the land of mimics for snakes,” says Strine. “Most of the highly venomous snakes also have a non-venomous mimic counterpart.”

"This is true of the mock viper, which has the triangular head, cryptic colour pattern and enlarged front teeth of its lethal relation. But it also appears to have gone a step further and evolved to change the shape of its rounded pupils into the vertical slits typical of a venomous viper when attacked.

"Strine's team was intrigued by the event and wanted to see it again. So, over the last four years of a biodiversity project in Thailand, they captured 36 individuals showing this behaviour.

"One question is whether it evolved as part of the snake's elaborate mimicry. “We are not even sure if it is a defensive strategy or just something that happens when the viper is gripped,” Strine says.

"Another possibility is that vertical pupils appear less conspicuous, helping the snake obscure the outline of its head. Or it could be that constricting its pupils improves the mock viper's vision, so increasing the accuracy of its defensive strike.

“'I would love to look at this behaviour in a controlled lab setting because it may be that the behaviour has limitations based on aggressor species, stimuli and other environmental factors,” Strine says.

“'It's a very interesting observation but, as the authors say, it raises lots of questions,” says Gonçalo Rosa at the University of Nevada in Reno. “If this is indeed a defensive strategy for mock vipers, it is possible that we might find it in other species that share their habitat with true vipers.'”

Comment: It certainly does raise questions as to how it evolved. Did this snake watch real vipers and learned how to change pupil shape? Not likely. When they evolved did they share common genes from a common ancestor? But this is a separate species, and this commonality is not mentioned in the article. Back to God stepping in? No clear explanation.

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