Scientists in the US have solved one of the biggest mysteries in evolutionary biology - how the penis develops, and why animals such as snakes and lizards have two, while mammals and birds are stuck with one. The research reveals that, in reptiles, the penis grows from the tissues.
Dolphins have retractable, hand-like, penises that grope around for the slugs regenerate the penises and are ready to do it all over again. 2.
Echidnas are spiny anteaters with four-headed penises. You read that correctly; when an echidna is having disgusting sex with a lady, two of its heads do.
From the pig with testicle eyes to the shark with a penis on its head: The From a two-headed cow to a piglet with TESTICLES for eyes, here.