Under the cover of night, two large leopard slugs begin to court, circling each other, before climbing single-file up a tree or onto a rock. They lower themselves on a mucus rope, while entwining their bodies in a strictly anti-clockwise fashion. Both slugs then push out and entwine two overly-sized penises from openings on the side of their head, before exchanging sperm that may later fertilise each of their eggs. Or, perhaps be eaten.
Everything You Never Wanted to Know About Snail Sex
Zoologger: Sea slugs stab partners in head during sex | New Scientist
A love dart also known as a gypsobelum is a sharp, calcareous or chitinous dart which some hermaphroditic land snails and slugs create. Love darts are both formed and stored internally in a dart sac. These darts are made in sexually mature animals only, and are used as part of the sequence of events during courtship , before actual mating takes place. Darts are quite large compared to the size of the animal: in the case of the semi-slug genus Parmarion , the length of a dart can be up to one fifth that of the semi-slug's foot. The process of using love darts in snails is a form of sexual selection.
We Just Found Out About Leopard Slug Sex And It's So Weird That We're Mesmerised
Under the cover of darkness, leopard slugs perform a bizarre, balletic and very colourful mating ritual. A leopard slug's huge blue-tinted penis and upside-down reproductive acrobatics make for a colourful sex life. Twisting their slimy bodies together, the large slugs dangle upside down from a glittering rope of mucus, slowly rotating. If you come across this weird sight, you'd be forgiven for thinking the slug's wriggling blue protrusions were some sort of parasite, or even emerging young.
If you read this column with even the slightest regularity, you know that the animal kingdom has no shortage of weird sex. Like that of the parasite that devours a fish's tongue and mates in its mouth. Or the little marsupial that has so much sex it bleeds internally and goes blind and dies.