Tuesday, September 11, 2007

Philinopsis gardineri at Lau Lau

I did my typical 4 dives this past weekend, one at Lau Lau and Grotto each on Saturday, then I reversed it for Sunday. It wasn't one of the better nudibranch weekends, of course I found a handful to take pictures of. At my Sunday afternoon Lau Lau dive, I went out looking for turtles first, but got skunked on that count. So then I worked my way in along all the big rocks and coral heads near the pipeline, still nothing. I had been out for a little over an hour, and hadn't found a single thing to take a picture of, pretty unusual for me. I decided to cut back over and go looking through the sand fingers hoping to stumble across something. That's when I found this threesome of Philinopsis gardineri nudibranchs all curled into a ball. Now this was either a nudibranch team sport, or they were going at it and putting on a mating show for me. Why is it that nudibranchs seem to want to perform for me? Is it just because I always have a camera in my hands these days? Is it that they are all hoping to get into a book somewhere? Fortunately I still had about 1900 pounds of air in my tank, so I decided to just lay there and watch these guys for a while and see what happened. I spent the next hour and a half just sitting in that one spot waiting for them to do something. It's not quite as action packed as watching mold grow, but it's very close. But persistence paid off as one of them broke off from their little group hug and headed about 8 inches away. He started pushing his head down into the sand and he seemed to move the sand up his body, gradually covering more and more of his body with the sand until he was completely covered. Now this wasn't exactly a fast process mind you, I'd guess it took a good 5 minutes for him to finally completely cover himself, but I had plenty of air and was kind of intrigued by this point. Now it's not like he was pushing the sand out of his way and moving forward, he was piling the sand up on top of himself, somehow moving it along his skin. He stayed in basically the exact same spot but buried himself by moving the sand further and further back on his body, until as you can see in the last picture, there really wasn't anything left showing of him at all. Then once he was completely covered in sand, he did start working his way to the side. I know that this particular type of nudibranch will go under the sand to hunt for bubble shells and worms that it eats. So are nudibranchs like people and want a snack after a vigorous bedroom workout? It didn't really look all that vigorous to me, but I suppose that could still have been the motivation. Or did this have something to do with the mating ritual?

As I stayed there and watched, the other 2 eventually did the same thing, both crawling several inches away, then they proceeded to bury themselves as well. And I don't know if the mysterious cocoons in the sand flats at Lau Lau have anything to do with this particular nudibranch or not, but there was one about 8" away from where they were making whoopee. So I don't know if the cocoon has anything to do with the nudibranchs or not, but I do plan on going back this afternoon to find out if there are 3 more of them where each of those guys buried themselves. I'm sure that the nudibranch experts have all the answers to my questions, however there is something to be said for investigating for yourself and discovering things through observation. But then again you never know, it's amazing how many things having to do with nudibranchs are relatively unknown at this point. That makes it even more fun to look into!