Mysterious Evolution of Shark Penis: Blame Sonic the Hedgehog?!

Here's something you probably didn't know. Sharks, skates, and rays - everyday Chondrichthyes - boast some very strange sexual organs. Like a pair of clasper-like penises, the male sex organs of a shark literally hook inside a female shark's cloaca in a unique reproductive strategy. Now, researchers think they have finally determined how these animals developed such strange members.