Wednesday, September 12, 2007

It's Confirmed!

Mike Tripp and I headed out to Lau Lau Tuesday afternoon to see if we could find anything else out about the Philinopsis gardineri nudibranchs and the cocoons that seem to be connected to them. In my previous post I talked about watching 3 of them mating, then I watched as each of them wandered a few inches away and proceeded to bury themselves in the sand. Yesterday was 2 days after I witnessed the mating ritual, and sure enough right there in the exact spot that each of them buried themselves, there was now a cocoon floating in the water attached to the sand. So I considered that positive proof that these cocoons were indeed related to the mating of this particular nudibranch. Then with a little investigation on The Sea Slug Forum, I found pictures of another nudibranch spawning. It's not the exact same nudibranch, but in the same general family.

From reading that particular post on Sea Slug Forum I learned that these cocoons are actually egg masses. The nudibranch wraps the egg string around its body, then coats it with mucus, and pushes it off of the head end of its body leaving the cocoon shaped structure. The little string holding the egg capsules together is called the chalaza and is a characteristic feature of opisthobranch egg masses. The number of eggs in each capsule varies from species to species, some only have one egg per capsule, while others, such as some species of Aplysia can have 40 or 50. So the next time you're swimming over the sand flats at Lau Lau and you see all those little cocoons attached to the sand and swaying in the current, you will know they are actually egg masses laid by the Philinopsis gardineri nudibranch. The more we learn about our oceans and all the inhabitants of it, the more we can try to protect it. This is obviously the mating and spawning season for this particular nudibranch as these cocoons are popping up all over in the sand flats. So if you're swimming over the sand out there, be sure to keep your fins safely above the bottom so as not to disturb these delicate egg masses.

5 comments:

scubatripp said...

Got some video of the swaying egg masses and will try to get it up on my blog today.
Nice work on the research. Last time I saw these at Lau Lau there was about 3 or 4 days in a row where there was not just one or two but hundreds in one small area near the pipe and the anemone.

Bob Abela said...

Hey, great observations Harry. I've seen these before and, like yourself, had sometimes wondered what they were. So thank you for sharing your observations and research. Very informative and I'll be sure to pay closer attention to them next time.

Bruce A. Bateman said...

Nice detective work, Harry. Mike, I'm looking forward to that video footage.

I wrote a short bit about haphazard walking on reeftops earlier in the week. I'm getting a little negative feedback, no biggie, but it would be nice if everyone who shares the ocean space would be a little more careful.

Education is the key. I might have picked one of those egg sacks up to examine it more closely and damaged it by accident.

You and Mike and Marianas Dive are doing a good service educating us un-nudi-conscious swimmers and divers. And they look cool too.

Paros Shepherd said...

Thanks for the insights. It reminded me of one of my snorkel discoveries, a spotted sea hare.
More at: http://parosparadise.blogspot.com/2007/07/spotted-sea-hare.html

The Saipan Blogger アンジェロ・ビラゴメズ said...

I wonder how they taste?