The world's sexiest animal is revealed

A tiny relative of the water fleas that readily breed in suburban garden ponds is thought to be the world's sexiest animal.

A tiny relative of the water fleas that readily breed in suburban garden ponds is thought to be the world's sexiest animal.

Scientists have identified the sexually aroused male member, the oldest sexual organ on record, in a fossilised ostracod that is 100 millions years old. The ostracod is a pinhead-sized crustacean, a distant ancestor of water fleas and shrimps, that lived for sex, according to David Siveter, professor of palaeontology at Leicester University.

"If you have a garden pond, you have ostracods. They have the longest and most ostentatious display of sex of any animal group in the fossil record. We can identify males and females back to 500 million years," Dr Siveter told the Science Festival. "Ostracods are very sexy animals. They have the second longest sperm in the animal kingdom. A one-millimetre ostracod can produce a single sperm that is 10mm long. It clearly has to have special equipment to deal with this sperm and it doesn't have one penis, it has two.

"Clearly all their apparatus is geared to sex. A male ostracod one millimetre long has a penis one third the size in volume of its entire body and it has two of them. So it gives a lot of attention to sex."

The oldest penis was found in a fossilised "fish nodule" of rock, which was collected in Brazil and is now held at the Natural History Museum in London, although it is not on public display.