Thursday, March 01, 2007

Hawaiian Spanish Dancer Nudibranch

So last night we did the night dive and came across a Spanish Dancer Nudibranch (Hexabranchus sanguineus). These are the lagrest nudibranchs found in Hawaii. I was quite excited and pulled out the camera and took a few shots.... I could tell they turned out looking at the monitor, but it got better.... I saw something else.

Spanish Dancers can grow to up to at least 15 inches according to John Hoover's book "Hawai'i's Sea Creatures" (linked on the sidebar of this page, it's the best invertebrate book you'll likely find on Hawaiian critters). They have fairly large eye stalks (the two red things on the lower part of the picture) and an impressive frilly gill structure (nudibranch translates into "naked gill"). Occasionally, and this is the really exciting part, they pick up hitchhikers. If you click on the picture above to view it in larger mode and look at the frilly gill structure, you might notice something slightly out of place with a large white patch... look closer....

Just in case you don't see it, here's an enlarged view of the gill structure section of the same photo.... WOW!! (although I wish it came in clearer). Do you see it now?

My camera isn't really set up to take shots at night. If I find something I want to take a photo of I have to shine a light on it at a distance that won't scare it and then try to hold the camera still enough to get a focus lock and hope the flash is enough to light up the whole subject. In this case what I noticed in the gill structure was an Imperial Shrimp (Periclimenes imperator). These shrimp tend to match the color of the nudibranch and are not very common. We see similar shrimp on other critters (sea stars and urchins and such) but they're usually much smaller. Here's a closer photo I took, gotta warn you it' not in focus though, it was practically running from my light.

As for the rest of the dive, we had one manta for the entire dive (showed up right under the boat and swam along with us and a group of the next boat towards the dive site). The water temperature read 73 degrees on my computer, but it seemed warmer than the 73 I dove in a couple of weeks ago (this was my first dive since my little calf boo boo).




Becca said...

Very cool! Thank you for the education. Great photographs!


Just a Girl from L.A. said...

Love your blog! I'll be in Maui in April! :)