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Tarantulas are large, hairy spiders which are mostly nocturnal. Scientists were not sure why they need such bright blue and green colours. Tarantulas were also thought to be colour blind. Now, researchers from Yale-NUS College and Carnegie Mellon University have found that tarantulas can indeed see in colour, and vibrant blue colours may be used to attract mates. The green colour might help them hide among the leaves (Proceedings of the Royal Society B).
The team reconstructed the colours of tarantula ancestors across 110 million years and found that they could have been mostly blue in colour. They noted that the blue colour did not correlate with any common defence mechanisms, showing the colour did not evolve to deter predators but to woo a potential mate.
“Our finding that blueness was lost multiple times in the New World, while regained in the Old, is intriguing. This leaves fascinating avenues for future research when considering how the ecological pressures in the New and the Old Worlds vary,” said one of the authors Vinod Kumar Saranathan in a press release. “For instance, one hypothesis would be differences in the light environments of the habitats between the New and the Old World, which can affect how these colours might be perceived if indeed they can be, as our results suggest.”
