For some species of fish, reproduction is beyond casual. Females release eggs into the water, males release sperm, and the eggs get fertilized. No physical contact involved. Just a few species prefer internal fertilization—that is, fish-on-fish action. And this is where the technique gets interesting. Male sharks and rays have special organs called “claspers” that help them do the deed. While that may seem wild, nothing is stranger than fish of the genus Phallostethus. Phallostethus cuulong (Greek for “penis chest”) has genitals on its head. The male uses a bony organ on his chin called a priapium to hang on to the female’s urogenital opening, which is also on her head. Talk about dirty minds!