Monthly Archives: March 2019

More flotsam

The water at Mahukona was full of floaty stuff yesterday.  This happens fairly often, when the prevailing tradewinds die and are replaced by on-shore breezes.  The on-shores bring in plankton and all sorts of other things from deeper offshore waters.  Sometimes they bring stinging jellyfish (as described in the December 2016 post entitled The Pink Menace), but yesterday it was primarily tiny, nearly invisible creatures, which the various species of plankton-eating reef fish rose up to dine on.  (Yeah, I know, dangling participle.  I’m pretty sure it’s allowed in this rapidly unravelling 2019 world.  Heck, if the President can say “bullshit” at a rally, I guess I can dangle a participle.)  The upper water column was loaded with feeding Hawaiian Sergeants, Indopacific Sergeants, Black Durgons, Thompson’s Surgeonfish, Milletseed Butterflies, and others.

The great thing about days like this—and ocean snorkeling in general—is that you never know what else will drift in.  In this case it was a tiny creature bobbing around randomly in the upper few feet of the water column, in water about ten feet deep. It was rolled up into kind of a lumpy ball shape about half an inch across, and we initially had no idea what it was—animal, vegetable, or mineral; alive or dead.  But it looked intriguing enough that I had to play with it.  When I handled it, it opened up into a flatter shape, and appeared to try, slowly and not very efficiently, to swim away.  With our presbyopic vision, we still couldn’t figure out what it was, so I took some pictures and we let it go on its way.

When we got home and looked at the photos we saw that the object of our interest was a Gold Lace Nudibranch.  This is apparently a common endemic species, but neither of us had seen one before.  It’s usually, like most nudis, found crawling on the bottom.  I did a Google search and could only find one photo of a Gold Lace swimming freely.  I guess this one was trying to move to a new neighborhood.  Here’s what it looked like:

Our free-swimming Gold Lace Nudibranch. Out in the water we weren’t able to make out the frilly little blue-black protrusions in the photo. Once we looked at the photo it was clear that these structures were rhinophores and gills—organs possessed by nudibranchs. (All nudibranchs, aka sea slugs, have external gills—nudibranch means “naked gill” in Latin.  Most, if not all, also possess rhinophores, an external chemosensory organ.) With the help of John Hoover’s Hawaii’s Sea Creatures we figured out that this was a Gold Lace. The species barely reaches an adult length of two inches—this one was probably a little under an inch fully unfurled.

Here it is completely unfurled in my hand.  I’ve never seen a photo of this species with wings like this. Their bodies are normally more elliptical. Maybe they assume this winged shape when they swim.

We often run into floating debris when the on-shores are blowing.  Objects that have been in the water for any length of time accumulate marine growth, and often a collection of juvenile fish using the object for shelter. A lot of different fish species congregate around floating objects as juveniles, prior to settling out on the reefs as they get a bit older.  Individual species are difficult to identify, partly because the popular books don’t typically show this stage.

Juvenile chubs (I’m pretty sure they’re chubs) nervously clustered around a floating plastic bottle. We always make sure to examine any marine debris we encounter, either while snorkeling or kayaking.  The pleasure of never knowing what you’ll find.

A foraging Eagle Ray

Spotted Eagle Rays are a pretty common—and always welcome—sight on Hawaiian reefs.  Usually they’re either milling around or cruising from point to point, often in small groups.  Sometimes we see them foraging in the sand for buried invertebrate prey.  This one at Mahukona foraged for several minutes, ignoring us as we watched.

Rooting around, creating clouds of sand.  Eagle Rays are believed to have special sensory organs in their snouts that detect the electromagnetic signatures of their buried prey.

A closer look at this medium-sized ray, about four feet across.  The multiple poisonous tail barbs, as well as that cool looking vertical tail fin are apparent here.  This individual, like many, is kind of beat-up looking, the snout in particular showing the wear and tear of years of rooting around in rocky sand.  Hoover tells us that Eagle Rays have among the highest brain to body size ratios of any fish.  (Morays have among the lowest.)

Here’s a smaller specimen we ran into at Makaiwa Bay last week.  It’s lost its tail, probably to a would-be predator.  Broken tails are not uncommon, but usually the loss involves just the long, filamentous portion. Like so many fish, this one seems to be coping with the mutilation quite well.

 

Some South Kohala eye candy

Last week Marla and I took a couple of dives off Puako with Blue Wilderness.  There were a handful of beginners  on the boat this day, so we dove two shallow sites—about 40 feet.  Neither site was all that exciting, but both were quite fishy, full of the usual suspects.  Here are some of the prettier or more interesting ones:

I still sometimes have trouble distinguishing between the Big Longnose Butterflyfish* shown here and the similar (not big) Longnose Butteflyfish. This photo highlights two distinguishing features of the Big Longnose—an extremely long snout and a sprinkling of black flecks on the chest.

A handsome adult Orangebar Surgeonfish.

The pale fish near the center of this photo is a juvenile Orangebar Surgeon, together with some Goldring Surgeonfish, Brown Surgeonfish, and Yellow Tangs. Like I said, a pretty fish-rich site.

A young Yellowtail Coris with a couple of juvenile parrotfish (two different species it looks like).

A juvenile Banded Urchin (right) and a Rock Boring Urchin (left). I’d never seen a juvenile Banded Urchin before. The flattened spines (which disappear on adults) are unique and rather eye-catching. That Rock Boring Urchin has actually excavated the hole into which it is nestled.

A tiny Trembling Nudibranch, only about a half inch long. I’d have never spotted it without the help of our dive guide. Regular readers (ha, if there are any) may recall that we saw one of these on a piling at Kawaihae last year.

An enormous Stripebelly Puffer. This thing must have been a foot and a half long. Hoover says it’s Hawaii’s largest puffer. We frequently run into smaller specimens snorkeling at Mahukona and other sites.

*I’m using Hoover’s nomenclature here.  Reef.org and many others call the Longnose Butterflyfish the Forcepsfish and refer to the Big Longnose Butterfly as Longnose Butterfly.  Some use Common Longnose Butterflyfish for the Forcepsfish.  Sheesh.

Mahukona hermits

After returning from yet another mainland trip the other day, Marla and I took a fast, cold snorkel at Mahukona.  Marla wanted to keep moving in order to stay warm, and I followed.  It was nice and clear and fishy, but we didn’t really see anything of interest, and Marla soon went in to enjoy Mahukona’s solar-heated “shower,” a hose bib fastened to a rock wall in the parking lot.  I decided to linger for a while near the dock.  The area close-in to the dock is surprisingly productive—it’s the only place in Hawaii where we’ve seen Leaf Scorpionfish*, and we’ve spotted all sorts of eel there, as well as hybrid tangs.  This day the surprise was a sizable group of Hawaiian Elegant Hermit Crabs huddled among some large boulders in the surge zone just a few feet from the dock wall.  These little beauties are not uncommon, but I’d never seen so many at once—at least ten.

Hawaiian Elegant Hermit Crab living in the shell of a Mulberry Drupe, another common species.  The shell is about an inch across.  Check out those striking blue eyes!

Another hermit, this time in a shell I can’t identify.  (Probably easy to identify, but whatever it is, it doesn’t appear to be in Hoover’s Hawaii’s Sea Creatures book, which is my only handy resource.)

Coming back in toward the ladder I ran into a more tame than usual pair of Sailfin Tangs. This one accommodated my desire for a photo by flaring its dorsal fin.

*As of this post I’m capitalizing English common names for fish and other creatures, joining John Hoover, my good friend Jeff Hill, and many others.