Tag: nudibranch

Postcard from the Reef – Not a Nudi

Two dives, almost two hours underwater, much of that time spent combing the reef face and cave walls for small invertebrates to photograph. I was well into my second dive of the day, a nice cave called Henry’s, where I had now spent over forty minutes carefully searching the interior and entrance areas of the lava tube. My real target is nudibranchs, but so far the day’s diving had revealed only two, both species I had found and photographed many times before.

A splash of color at the base of a large antler coral got my attention, it was shaped just right, but I was not in a position to see it clearly. Getting closer it looked better, about the right size with white raised features. It was only after circling to the other side of the coral and getting in close that I saw that this was probably not a nudi. It took a moment to realize that this was probably a dark purple sponge with bright white osculum. Even in the photo you have to look close to realize what it is.

Except in a few obvious cases, I make no real effort to properly identify sponges. This is a task that takes an expert, a collected specimen and a proper lab to do. I did check briefly through the book to see if there was a clear match, but as I expected, this sponge will remain identified simply as… a sponge.

Not a Nudi
A colorful sponge mimics a nudibranch

Postcard from the Reef – Reef Rose

With the appearance, size and color of a rose, the moniker Reef Rose seems to fit. In reality these are the eggs of a large nudibranch, the Spanish dancer. Not at all hard to spot, I had been finding these for years before actually seeing the parent.

I always make a point to check the egg mass closely. There is another nudibranch, a tiny parasitic nudibranch that eats the eggs of the Spanish dancer, a species unsurprisingly called the egg-eating nudibranch.

The eggs of a Spanish Dancer nudibranch (Hexabranchus sanguineus) at Three Tables, Oahu

Postcard from the Reef – Pustulose Nudibranch

The most common nudibranch I find on Kohala reefs. These fellows are active in the daytime and often found in the open. They are generally found on walls, or in the many small caves that penetrate local reefs.

Pustulose Nudibranch
Pustulose Nudibranch (Phyllidiella pustulosa) on a wall at 25′ depth, Puako

Postcard from the Reef – Sphinx Nudibranch

From a distance it looked like another common P. varicosa, a nudibranch I see all the time on the reef. Getting closer something was different. No protuberances, no yellow, what was it? Simply a juvenile that has not developed the full colors and pattern? Not knowing what it was I proceed to take a few photos of the critter.

Hitting the books it quickly becomes apparent, it was a P. sphingus I found and photographed. A new species for me! I carefully read through the descriptions of the various dorid nudibranch found in Hawai’i again. I need to look closer, there are some lookalikes to be aware of.

Sphinx Nudibranch
Sphinx Nudibranch (Phyllidiopsis sphingis) at 25′ depth, Puako

Postcard from the Reef – Rosy Phyllidia

A nice day for a dive, and a new species of nudibrach for me. At first I thought it might simply be a juvenile P. varicosa, but there were no yellow pertuberances. Getting back I hit the books, no doubt, P. rosans. New species! This fellow was in a cave at Puako I have entered a dozen times. Even in a place I have often explored I can find something new…

Rosy Phyllidia
A Rosy Phyllidia (Phyllidiella rosans) in a cave at 25′ depth, Puako

Postcard from the Reef – Spanish Dancer

What is that? That is too big to be a nudibranch, but that is what it looked like. I could only see part of the beast looking into the cave crevice. Fortunately it turned out to be somewhat photophobic, the bright light flushed it out of the crevice into the cave…

Spanish Dancer
Spanish Dancer (Hexabranchus sanguineus)
A Spanish Dancer!

I make a point to look for nudibranchs, pretty critters that are wonderfully photogenic. Looking into the nooks and crannies of the reef for nudibranchs also tends to turn up other tiny surprises.

This was not small!

While the typical nudibranch is one or two inches long, this fellow was the size of a dinnerplate! Adding to the wonder was the dance. As soon as the animal left the crevice it swam across the cave. I flashed Mark to get his attention, he was ready to leave the cave. I suspect he is glad he came back. Deb also wondered what we were still doing in the cave and came in to check on us. Thus we all got a good look at the dance.

After a few photos… OK, a lot of photos, I shepherded the fellow back into his crevice. Once I withdrew the light he settled down to stay in the darkness.

Spanish Dancer
Spanish Dancer (Hexabranchus sanguineus) swimming in a cave at the Dotti’s Reef dive site north of Honokohau

Postcard from the Reef – Nudi Eggs

A little spiral on a rock, an odd looking thing, a bright white against the reds and yellows of the sponges. I spotted the spiral from some distance away across the cave. But I know what to look for, sweeping the rock with my dive light.

The nudibranch themselves are nearby, on the same face of the rock. I find three white-margin nudibranch, two quite large at about 3cm, the largest I have seen this species. A much smaller specimen is close by, less than half the length of the adult. These are a handsome species, always nice to find.

White-margin Nudibranch Egg Mass
White-margin Nudibranch (Glossodoris rufomarginata) egg mass

I am surprised that the eggs are not quickly eaten by fish or other predators. There must be some defense mechanism in play, a foul taste, a toxin, nudibranch are known to employ such tactics.

White-margin Nudibranch
A pair of White-margin Nudibranch (Glossodoris rufomarginata), 25ft depth at O'oma