by Danielle Owczarski
During the first cold days of fall in Burlington, I had a chance encounter with a handsome slug on my way to catch the bus. As I hurried past, it glided effortlessly across the moistened slate walkway, its black leopard-print pattern catching my eye. The image of the mysterious figure drifted through my thoughts during the short bus ride to campus.
Limax maximus, also known as the great gray slug and leopard slug. (Photo:© R.J. McDonnell, University of California, Riverside)
Originally, when I thought about writing a blog on the natural history of the great gray slug (Limax maximus), I imagined the story to be a simple, thoughtful, interesting piece; little I knew of the great gray’s sensual secrets. Those of you with weak stomachs or other sensitivities related to natural reproduction may want to surf your way to a blog about cooking or kittens. This story is for those with unquenchable curiosity and a sensible grasp on nature’s sexual exploits.
The great gray is a hermaphrodite. Within its slimy skin layer are organs that support both female and male reproduction. Lucky for the great gray, it is not a simultaneous hermaphrodite like the banana slug, who can self-fertilize. No, the great gray must entice a partner to share in the event of reproductive triumph.
L. maximus, native to Europe, and naturalized in the United States and Australia by way of food transport, leaves a thick string of mucus on the ground in early summer to attract its mate. This activity happens mainly during the night hours for this nocturnal species, who feeds on mushrooms and withered plants.
When its partner detects the secretions, it will follow closely, taking a soft nibble on the tempter’s behind. In a grand chase (at a slug’s speed), the two head for an overhanging feature (a brick wall, tree, or mossy rock). They begin to writhe in what seems a blissful engagement, rubbing and twisting around each other’s lubricated bodies.
As the foreplay advances, they begin to fall gently from their perch, attached only by a dense strand of slime, their pendulous bodies entwined in mid-air. Next, in unison, from an opening (gonopore) on the side of each slug’s head, the penises emerge and begin to entangle. The elaborate spiraling of the white translucent penes forms the shape of a flower similar to that of a blossoming morning glory. The unified form then takes on an azure glow and fertilization ensues. The sperm travels up through the twisted organs, through the gonopores, and inside the slug’s body finally reaching the eggs. The act is complete, both fulfilling their reproductive desires.
It would be biased to leave you with an unspoiled depiction of the great gray’s reproductive story. On some occasions when the entanglement becomes too complex and the slugs are unable to pull apart, apophallation must occur. They chew off one or both penises to relieve the imbroglio and the great gray is left with one working organ to continue its life’s work.
For those of you who can’t get enough, check out David Attenborough’s video clip of the great grays in the act: Limax maximus Reproduction Video.