Leaf Scorpionfish reappear—and disappear

Decades ago Marla had a sweet old German shepherd named Maddie. As with every other dog she’s ever owned, Marla walked Maddie through the neighborhood at least daily. One day, passing a certain house a few blocks from home, Maddie spotted a rabbit and got the chance to excitedly chase it until she came to the end of her leash. This was apparently a big event for her. For years afterward she’d linger when she passed that house, in hope of seeing the rabbit again. Sadly, she never did.

I’m something like Maddie when it comes to unusual reef fish. I’ll return over and over, sometimes for years, to spots where I’d seen something special like a Leaf Scorpionfish or a Gargantuan Blenny. Sometimes it pays off. We first encountered Leaf Scorpionfish among the rocks near the Mahukona dock in November 2016. We went back to look for it a few days later and it was gone. From then on we made a habit of scanning the area for this fish on most of our Mahukona snorkels. Our perseverance paid off in July 2017 when we saw not one, but three Leafs dispersed near the dock. These, too, disappeared within a few days. One reappeared for a short time later in the summer and disappeared again. So after two discrete successes we naturally continued surveying the area, with no luck until last week, when a single, ivory-colored Leaf Scorpion appeared just a few feet from the swim ladder. A day later it was accompanied by another, smaller, darker specimen—maybe a mate. A day after that both were gone. I wonder where to these sedentary, relatively immobile fish disappear to for months on end. My guess is that they’re just hunkered down deep in the reef, safe from the prying eyes of us two-leggers.

Intricate patterns and textures, and those strangely vacant eyes. 

A rare morph of a common fish

Whitemouth Morays are pretty much everywhere on Hawaiian reefs. We see at least one poking its head out of the coral on most of our snorkel outings. Most are brownish with a dense pattern of small white spots, the size and density of spots varying quite a bit. On rare individuals the spots almost merge, resulting in the appearance of a white background with brown reticulations. We ran into this morph the other day at Mahukona.

All Whitemouths are handsome fish, but the reticulated morph really stands out. This form is uncommon enough that there are no photos of it in either Hoover’s or Randall’s* books. (Hoover does mention this morph though.)

This is a more typical Whitemouth. The spots can often be larger and the background less reddish. In general, the larger the individual the smaller and less dense the spots. (At least that’s my impression.) This specimen is somewhat larger than the one in the top photo.

Another photo of the first eel, just for anyone who doubts that this is a Whitemouth. The white inside of the mouth (as well as a white tail tip) is a definitive identifier of this species.

*See the “About” page of this blog for Hoover’s and Randall’s books.

Cute eels

Morays are common and conspicuous on Hawaiian reefs—considerably more so than other places we’ve snorkeled or dived, such as Samoa and Bali. John Randall in Reef and Shore Fishes of the Hawaiian Islands attributes this difference to Hawaii’s geographic isolation. Since the Hawaiian Islands rose from the ocean quite recently, geologically speaking, everything that lives here has to have colonized the Islands from somewhere else.  In the case of reef fish this somewhere else is the South Indopacific and East Asia. Morays have a prolonged planktonic larval stage, allowing them to drift far enough in the open ocean from their ancestral homes to become established in Hawaii. In contrast, fish groups that compete with morays—specifically snappers and groupers—have shorter larval stages and hence have not become established here. (Hawaii therefore has few native shallow-water snappers and no groupers, although some have been introduced).  Morays then occupy ecological niches that are held by snappers and groupers in the much less geographically isolated South Pacific islands.

Most morays eat fish. To accomplish this their mouths are full of sharp teeth, giving them a nasty, dangerous appearance. A few morays are crab eaters though. These species have blunt rather than sharp teeth—the better to crush their prey’s shells. So they lack the sinister look of their toothier brethren, actually appearing quite benign, even kind of cute. Here are a couple examples we’ve seen recently:

We see Zebra Morays often, but they are usually nestled deep in the rocks with only isolated portions of their body visible. Even when the head is exposed these slow-moving eels seem pretty much oblivious to the presence of humans. This one, at Puako, bears a particularly innocent, almost puppy-like countenance.

Another blunt-toothed species, the Snowflake Moray is to me Hawaii’s handsomest eel. These guys are often seen swimming in the open, completely unfazed by—but clearly aware of—the close presence of a snorkeler or diver with camera. This one was near the dock at (where else?) Mahukona.

Another Kawaihae oddity

Marla, Hai, and I spent yesterday morning snorkeling among the pilings in Kawaihae Harbor. This place is a fantasyland of odd invertebrates and fish. A bewildering variety of organisms grow attached to the pilings—colorful sponges, corals, hydroids, seaweeds, nudibranchs, and many things we could not identify. While naturalists revel in this biological richness, people in the marine industries curse these fouling organisms, viewing them as nuisances to be discouraged or killed.

All this growth attracts fish. Many of the usual reef fish—surgeonfish, wrasses, butterflyfish, Moorish Idols—cluster around the pilings. The habitat is especially attractive to juvenile fish, as it provides lots of places to hide from predators. On yesterday’s outing we ran across a juvenile Scrawled Filefish about five inches long. It hung vertically, head-down, nearly motionless, next to one of the pilings. Due to its coloration and stillness it was not easy to spot. As we approached, it tried to evade detection by slowly moving to the other side of the piling. We played hide and seek like this for several minutes, managing to get some good views and a couple of photos. While a bit wary of us, the little fish didn’t seem terribly bothered by our presence, once or twice taking a bite of sponge as we watched.

Juvenile Scrawled Filefish trying to look inconspicuous next to a fouled chain hanging in the water near the pilings. Jeff, Sandra, and Hai had seen one of these guys earlier this year, but it was a first for Marla and me. This species is, for obvious reasons, also called Broomtail Filefish.

A bit later it moved a few feet out into open water and allowed a closer view in better light.

Adult Scrawled Filefish, almost as strange looking as the juveniles, roam the reefs in a more normal fishy manner. This one was at Mahukona, where we regularly see them.

Crabs

We’ve been seeing a lot of interesting crabs lately. Or maybe we’ve just been paying more attention.  Reef-dwelling crabs form a diverse assemblage, filling a wide variety of ecological niches. Many, like shrimp, live symbiotically with other reef creatures. Most are quite attractive. Here are two that have posed for us over the last few weeks:

This crab is often called the Spotted Reef Crab, but here in Hawaii it’s more commonly referred to as the Seven-Eleven Crab. The latter name comes from the seven spots on top of the shell and four more on the bottom. These large crabs are mostly nocturnal, but on several occasions we’ve seen them while snorkeling at Mahukona during the day. All of our sightings have been in the late spring to early summer.  Perhaps this seasonality is related to mating activity. Seven-Elevens are found in many parts of the tropical Pacific. They’re eaten in many places, including Hawaii.

We found this Yellow-spotted Guard Crab hiding among the branches of an Antler Coral while snorkeling at Kihei in Maui. A handful of species of guard crab live mutualistically in branching corals.  As the name suggests, they protect the corals from intruders, including the predatory Crown of Thorns Starfish. In exchange for their protective duties the crabs get to dine on the corals—presumably in moderation so as to not destroy their hosts. Hoover writes that if you put your hand over a coral that harbors these crabs you will get your hand pinched. We didn’t try it.

Kawaihae south

At the south end of Kawaihae Harbor is a small boat marina where a couple dozen private sailboats are moored.  The marina is protected by a rip-rap breakwater that opens out into shallow, rather murky Pelekane Bay. The bay is known for its resident Black Tip Reef Sharks. Hai has seen and filmed these beautiful, harmless sharks on numerous occasions (see https://kawaihaereef.wordpress.com/2018/04/10/black-tip-sharks-at-pelekane-bay/) but as of last week Marla and I had yet to see them. In an effort to correct that situation, Hai and Lottie escorted us out through the marina into Pelekane Bay last week. We were successful in spotting these elegant, wary animals, but weren’t able to get any photos. We did, however, see and photograph some interesting creatures, both on the swim out through the marina and in the bay itself.

As soon as we entered the water at the marina Hai spotted this Wavy Bubble Shell actively crawling on one of the dock pilings. These unusual little mollusks are sort of halfway between snails and nudibranchs—they have shells, but cannot fit their whole bodies into the shells. Like many nudibranchs, they dine on toxic organisms (bristleworms in this case) and incorporate their prey’s toxins for their own protection. That’s what allows this delicate little animal to move around in plain sight. The pan-tropical species reaches a length of about 3/4 inch, which is about the size of this individual.

Just a minute or two later Lottie found this pair of Banded Coral Shrimp living on the underside of the dock. These shrimp, quite common in Hawaii and throughout the tropics, are usually found in pairs like this. They’re a type of cleaner shrimp, but are infrequently seen in the act of cleaning fish.  Hoover speculates that this is because they do most of their cleaning at night.

Out in the bay I ran into this Old Woman Wrasse. Hoover says this endemic fish is only common in the unoccupied Northwestern Chain of the Hawaiian Islands. We see them rarely at Mahukona; I posted a photo of a juvenile here: https://onebreathkohala.wordpress.com/2016/08/19/summer-juveniles-at-kahaluu/.  An alternate common name for this fish is Blacktail Wrasse, but the black tail is only found on terminal males. The Hawaiian name for this large wrasse, Hinalea Luahine, means old woman. This fish’s face has—to me at least—an oddly humanoid look, but not necessarily old woman-ish.

Small stuff at Kawaihae

Last weekend Marla and I snorkeled at Kawaihae Harbor, inside the breakwater, south of the platforms where the Army landing craft tie up. This is a warm, calm, relaxing place to snorkel—shallow, no waves, little wind. It’s also kind of barren relative to the sites we usually snorkel, with lots of dead coral, but several different coral species. And, like most sites, it yielded some interesting stuff.

We always make sure to visit the huge Plate and Knob Coral (Porites monticulosa) head southwest of the platforms. Oddly, this coral and others of its type don’t seem to be very attractive to fish. This lonely juvenile Convict Tang and a small group of juvenile parrotfish were all that we saw on this one. The light here allowed the coral to show through the fish’s translucent fins.

Cauliflower Corals attract all sorts of fish. This tiny Hawaiian Dascyllus plays hide and seek among the branches. 

There were a couple of wire corals growing from the boat ramp just a few feet off the beach. One was occupied by this Seawhip Goby. (Hoover calls it Gorgonian Goby.)  Earlier this year our friend Hai found  a couple of these fish living on a wire—not a wire coral, an actual wire— that hung into the water from one of the landing craft platforms. Hoover writes that this species can also be found on waterlogged twigs and pretty much anything else shaped sort of like a wire. The similar Wire Coral Goby is apparently more selective, usually confining itself to actual wire coral.