Sea Slug Love

I am on a bit of a roll lately. Living so close to the ocean in the Philippines, I get to night dive a lot, in a classic “muck diving” area. Last week I filmed a pair of pleurobranchs, Euselenops luniceps, mating. I was quite excited, so much that my air consumption went up and I was done after an hour, quite uncharacteristic for me. I don’t think there is much (if any) other footage of this mating behavior? I found videos of other pleurobranchs, Pleurobranchus forskali, mating.

The video also features a snail, likely Tonna sp. attacking a sea cucumber, possibly Holothuria sp., and squid, Loglio sp., frolicking and hunting in mid-water above the seagrass at night. All seen during one dive!!

A few weeks ago I filmed this unusual mating events, with three Pleurobranch slugs mating at the same time, in the sea grass. Given that each could play the role of the male, female, or both, how many combinations are possible with three slugs: