A penis would rank pretty high on any list of body parts you'd want to be able to grow back if lost. The more replacement penises the better. And for the first time, Japanese biologists have found an animal that can do just that.
The animal in question is the Chromodoris reticulata, a red and white slug found in Southeast Asia. A paper in the Royal Society journal Biology Letters says, No other animal is known to repeatedly copulate using such 'disposable penes'." It can do this at least three times, with approximately 24 hours required to ready each new penis.
Naturally, there are all some very scientific (and a little romantic) details about this as well. Each coupling lasts "between dozens of seconds and a few minutes". The new penis is thought to grow from a spiral shaped structure inside of the
male's slug's body (spring loaded penis!). And there are some backwards-facing spines on each penis, possible to remove enemy sperm and making it hard to remove without breaking off. So, uh, that sounds maybe more traumatic than romantic after all. [PhysOrg]