Picture details
Genus Pseudoceros
Species bedfordi
Authority Laidlaw, 1903
Family Pseudocerotidae
Order Polycladida
Location Helen's Reef, Puerto Princessa, Palawan, Philippines
Depth about 11 m
Date May 2001
© Copyright The Slug Site by Michael D. Miller
San Diego, CA, USA
Comments A quite rare photo document showing the complex mating behaviour of marine polyclads which has been recently described as an act of hypodermic insemination. During copulation worms were observed to move towards each other, touch, then roll around together (= "rearing up" - left photo), simultaneously everting their penis papillae and stylets outward. They then try to stab each other anywhere (= "penis fencing" - right photo). When one animal is successful in penetrating the other, it holds on with its stylet embedded in the epidermis of its partner and spermatozoa are transferred.

Check out the introductory page to learn more about the mating behaviour of marine polyclads!