Saturday, July 30, 2011

Ocelli in hindsight

Forest calotes sleeping
About a year ago I was musing over the spots on butterflies and most of it was about getting away from predators. On a recent visit to Rishi Valley, thanks to Dr Santharam, I spotted a female Calotes versicolor. Interestingly it had on the back of its head, two ocelli (false eyes, not to be confused with the functional simple eyes in insects). My impression was that this feature was more prominent in the Forest Calotes (C. rouxii).

Some years ago, I spotted the forest calotes on the right at night. I was not aware of the sleeping habit of these lizards until it was pointed out to by Saleem Hameed. They apparently always choose  the end of an overhanging tendril or branch which they clasp and roost. In the photograph of a roosting rouxii you can see the two eyespots on the back of the head.

A female C. versicolor, possibly gravid
The Rishi Valley Calotes appears to be a gravid female and has two ocelli. Perhaps I have not paid enough attention to this but the phenomenon of ocelli in more predatory species is apparently more widespread. It is also found a few falcons, hawks and owls. The white spots behind the ear of the tiger have also been pointed out as being similar.

Further reading

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