23 September 2009

I am talking about group sex...by snails

In 2 previous posts (Rumina saharica and Oxyloma retusum), I had pictures of 2 pairs of snails mating simultaneously. I also speculated that mating snails may exude a pheromone-like chemical in their slimes that excites nearby snails, causing them to start mating also.

About a half an hour ago I was looking at the miscellaneous natural history pictures that my facebook friend David Cilia had recently uploaded on his page. One of them was the following shot of 2 pairs of mating Cantareus aspersus (Cornu aspersum, Helix aspersa) on Malta.

DavidCiliaAspersus
Photo by David P. Cilia. Used here with his permission.

The snails are in what is called the face-to-face position (as opposed to the shell-mounting position). The union of the genital openings, on the right side of each snail's head, is clearly visible in the lower pair. They are supposed to have shot darts into each other. The object I marked with a red arrow may be a dart stuck into the right-hand snail's side.

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