Scientific American:

It can taste, smell and sing. It can be a corkscrew, a crowbar or a hypodermic needle. It can stretch up to nine times your body length (if you’re a barnacle); be a detachable tentacle covered in suckers (if you’re an argonaut octopus); or even see, using light-sensing cells that guide it smoothly to its destination (if you’re a Japanese yellow swallowtail butterfly). Or, it can be a limp, fleshy tube, hardly worth writing home about, if you’re a human.

It is the penis, as you’ll know if you’ve read Phallacy: Life Lessons from the Animal Penis, biologist and journalist Emily Willingham’s recent exploration of phallic diversity across the animal kingdom.

Go to link