spider sex!

From BBC:

Spiders "talk" to potential mates using a type of light not visible to the human eye, scientists report.

A team found that male jumping spiders (Phintella vittata) are using ultraviolet B (UVB) rays to communicate with females.

While UVA rays are often used in animal communication, this is the first evidence that UVB light is also being used, the researchers said.

The study is published in the journal Current Biology.

The team found that male spiders were reflecting the ultraviolet B rays from their bodies.

The researchers discovered that females were more likely to mate with males that could "talk" to them with UVB compared with spiders sitting in chambers where UVB light had been blocked with filters.