Red and white sea slugs that roam the warm waters of Southeast Asia just may be the envy of the animal world, given their ability to discard and re-grow a penis again and again. The Chromodoris reticulata is a hermaphroditic slug that, once mating is complete, can cast off its penis into the water. Twenty-four hours later, a new, fledgling penis unfurls from inside the slug, replacing the discarded one.
Japanese biologists reported in the Royal Society journal that these sea slugs are the only known animal to have a “disposable penis.” Each slug does in fact have both male and female genitalia, making them hermaphrodites. When mating with another slug, they fertilizes each other’s eggs in a sort of dual copulation, both storing the other’s sperm to inseminate their eggs.
After the deed is complete, the slugs then discard their penises, which prompts their bodies to begin growing the replacement penis. Around one day later, the new one emerges ready to inseminate its next partner.
What’s more, the sea slug’s penis has sort of a Darwinian streak to it. Biologists found that the shaft of the penis is covered in backward pointing spines that act as a cleaning brush. The spines remove the stored sperm of the slug’s previous partners, displacing their sperm to ensure their own is used for insemination.
Other animals, like starfish, can regenerate broken parts, but these red and white sea slugs are the only ones that can re-grow their manhood.
Via Phys Org