Spider confessed with ... ultraviolet rays

The spiders "chat" with their potential mates with a kind of light that the human eye cannot see. No species is known to use this light.

(Photo: BBC)

Professor Daiqin Li, from National University of Singapore, found in jumping spiders (Phintella vittata), males use ultraviolet B (UVB) to communicate with females.

Although animals often use ultraviolet A (UVA) in communication, this is the first evidence that UVB rays are also used. Males reflect the ultraviolet B from their bodies.

UVA and UVB rays are a small part of the sunlight range, but the human eye cannot see.

The team found that mating-like spiders could "chat" with UVB compared to those placed in rooms where UVB rays were filtered out.

"Most of the previous research focused on the phenomenon of animals interacting with UVA rays, but this is the first study on UVB in animals," Professor Li said.

"Until now, scientists have concluded that animals cannot see UVB rays, but we have found this to be incorrect."

Spiders have complex eyes and although scientists know they can sense UVA, they are still not sure how they detect UVB rays.