Tuesday, April 1, 2008

Halgerda Season in the Grotto

Well it's official, nudibranch season is alive and well in the Grotto. I've been seeing them sporadically for the last few weeks, but this past weekend I found over a dozen of these guys on one dive without even looking that hard. I also found a couple egg ribbons which means they have to be out looking for one another to meet up so they can reproduce. These little guys are one of the best kept secrets of the Grotto. Halgerda guahan (pictured above) and Halgerda malesso are fairly rare nudibranchs in the rest of the world, but during the season I can take you down and show them to you on any dive in the Grotto. Most tourists will never see these guys, because the dive guides don't take the time to get familiar with them and know where they hang out.
Most tourists are probably looking to see the big things underwater - turtles, sharks, Napolean Wrasse, eels, and I can understand that, those things are all very cool. And my love affair with turtles is well documented on my smugmug site, I have a bunch of awesome turtle pictures. But when you are only looking for the big stuff and ignore the tiny things, you are missing out on the most extraordinary things under the sea. And it's so exciting looking for the nudibranchs, it's like you're on a treasure hunt, and when you find one you've struck gold.
As I was slowly swimming over the big boulders in the Grotto, I came across these two Halgerda malesso feeding on the white sponges attached to the rocks. I have noticed that some of them have a lot of small yellow lines while others will have fewer lines and the patterns will be much larger. I'm not sure if there's any significance to that or not, but I thought it was interesting. I'm also intrigued by the way this particular nudibranch can make all the orange dots poke way out, making it appear like there could be spines in them. I'm sure that this is a defense mechanism meant to fool predators, but it gives them a very cool look when they do it. These nudibranchs can also flatten themselves out, usually when moving across a rock.
I followed this particular Halgerda malesso for a while waiting for him to get in position for just the right shot. Part of the trick to photographing these guys is to catch their gills and rhinopores at just the right angle as they are blown back and forth in the current. It means taking hundreds of pictures usually and sorting them out later to see what you got.
It is also fairly common to see the Halgerda guahan on the rocks covered with this purple vegetation, as it provides pretty good camouflage with their rhinopores and gills. I have seen them lay several egg ribbons now on these little purple hydroids. Yes, nudibranch season is back in full swing in the Grotto, and if you see some guy just laying in one spot taking picture after picture, it's most likely me taking a bunch of pictures of one of my favorite subjects. Come on over, I'd be happy to point them out to you!

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