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Elements: The Scientific Magazine
Science in Contex t
Really Slimy Sex M ary K rauszer
How Hermaphrodites do It Upside-down. Backwards. Hanging from a rope, all covered in lube. Slugs seem like relatively unimpressive creatures, composed mostly of slime, squish, and your mother’s daffodils, but where nature rations good looks, she delivers kinky compensation in spades. As hermaphrodites, slugs are uniquely concerned with the exchange of genetic material, or lack thereof. Many species are known to reproduce asexually when necessary (talk about desperate), but finding a mate is much preferred. It is in these two-goo encounters that the exciting stuff comes out, literally.
a penis from the genital opening toward the front of the mantle. Copulation occurs when these organs exchange genetic material, sperm passing from each to the other, followed by withdrawal. Beyond this standard schedule, speciation has given rise to some astounding variations on the slug-sex theme. Some of my favorites are described below.
Anatomy of the typical garden slug. Note: mucus has not been labeled. Assume it is everywhere.
Let’s start with some basic anatomy. Slugs are of the phylum mollusca and the class gastropoda, which characterizes them by their large single foot and that adorable double set of sensory tentacles. Just behind the eyestalks we find the mantle, another mollusk signature, which houses the sex organs, usually both male and female in a single individual. Slugga Sutra Typical slug mating can be broken down into four steps: precourtship, courtship, copulation, and withdrawal. Slime trails flavored with “Come and get me!” hormones initiate a patient pursuit as the slugs begin the precourtship behavior of trailing and following. After up to 10 hours of slinking around and getting in the mood for getting in the mood, courtship begins. The slugs finally make physical contact—encircling, nibbling, and excreting exceptional amounts of mucus onto each other. Toward the end of this junior high school dance encounter, each slug everts
The common European Red Slug, Arion rufus mid-copulation. The white blobs with a blue-ish tint are penises.
Leopard Lovin’: Don’t get hit in the face The leopard slug, Limax maximus, makes some interesting edits to the basic steps (which, thanks to David Attenborough, have made them YouTube stars). First, in the pursuit of precourtship, the leading slug scales a vertical surface, taking the pair to some kind of shelf or overhang, such as the underside of a branch. From here they do all the standard slug-cuddling, until suddenly they separate from the branch and slide down a rope of strong mucus, usually 10-30cm long. Suspended in midair (most Upside-down, hanging from a commonly at human mucus rope: for experts only. eye level*) the leopard Wikimedia Commons
Wikimedia Commons
Wikimedia Commons
Slug Anatomy