Mating in these strange-looking mollusks lasts for 2 to 3 hours, but it's unclear what exactly is going on during this time.
From an evolutionary and biological perspective, animals are driven to have sex in order to procreate. But there is a lot more to sexual relations between animals. Animal sex is at least as strange and varied as human sex. A male might copulate with many females. And female animals of many species can be choosy, too. Homosexuality is common. Monogamy is rare. And the animal kingdom is full of swingers. In short, with animals, sex can be wild.
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Biologist and writer Carin Bondar leads the way into the intriguing world of animal sexual practices in her new book, "Wild Sex."
Studying the sex life of flies might sound silly, but two researchers who did just that have saved the livestock industry billions of dollars.
These images reveal the Bombay night frogs have seven mating positions, with one that was just discovered in which the male is loosely draped over the female.
Scorpion sex usually involves peaceful dancing, but sometimes can also include stinging and cannibalism.
Tarantula mating involves sperm webs, courtship dances, and fang clasping. And sometimes sexual cannibalism.
In the months preceding Christmas, Santa's sleigh-pulling ungulates are engaged in a very different activity — mating. Reindeer sex involves herding, defending harems and ignoring lovers.