Say hello to this little tidepool goby. It's a frillgoby, in the genus Bathygobius, one of three frillgobies in Hawaiʻi. Is it a whitespotted frillgoby or a cocos frillgoby? Hard to tell, unless youʻre willing to count scale rows and fin rays (thanks for the i.d. help, Keoki Stender and the extensive website: MarinelifePhotography.com), but both are common in our tidepools, and both can display a banded pattern at will. The flathead, a.k.a cheekscale frillgoby is another possibility, though it tends to have a wider, flatter, and darker head. All the frillgobies here are small guys, getting no longer than three to four inches, and gobies in general, are small fishes, and bottom-feeders. The frillgobies tend to make good marine aquarium pets, as they are pretty happy-go-lucky towards tankmates, though not so much to their kin. Gobies are known for their fused pelvic fins that help them hold fast against the wave surges, or in the freshwater species, (ʻoʻopu wai) against the stream flow as well as in locomotion upstream to their niche. No matter that the force is not with them.
No mistaking the barber pole stripes of the Banded Coral Shrimp, Stenopus hispidus, who offer their own version of a close shave. These colorful decapods belong to one the families of cleaner shrimp known for plucking ectoparasites and injured tissue off of fish such as tangs and morays. Setting up shop in tide pools and shallow waters (though they have been observed at greater depths), the banded coral shrimp often advertise their services by hanging upside-down in a crevice or reef ledges and waving their three pairs of very long, white antennae. These can be two to three times longer than the body of the shrimp, which is around two inches or so, and are used to palpate those in need of cleaning, as well as serving as sensors to help the shrimp move about at dusk, when it becomes active. They run the mom and pop shops of the reef- they are often found in pairs patrolling, defending, and servicing a square meter or so of the fish-rich waters. They'll also munch on other sea fare if cleaning clientele are low. In the reef ecosystem, these candy cane shrimp certainly have earned their stripes.
Todayʻs post features the flashy and silvery āhole, as tasty today as they were in days of old. Their high tolerance for fluctuating salinities and temperatures made them an excellent choice for fish ponds, and they were also used in ceremonies "to chase away evil spirits and for love magic" according to Nā Puke Wehewehe ʻŌlelo Hawaiʻi. These flagtails have a deeply forked tail, large eyes, and can reach sizes around eight or so inches. During the day, adults school on or near coral reefs where they get plenty of wave action; at night they disperse to forage. Subadults can be found congregating in fairly shallow waters. Waiāhole on Oahu and Keāhole Point on the Big Island are two place names that reveal the prevalence and cultural significance of the āhole.
Until recently, it was thought that there was just one species of āhole here; fisherman, though, recognized two morphotypes, and recent DNA analysis* has confirmed the knowledge of the locals. Kuhlia xenura and Kuhlia sandvicensis are difficult to tell apart, but as juveniles (juvies are called āholehole) Kuhlia sandvicensis sport zebra-like markings on the head, favor tidepools with an open-water connection, and do not appear to venture well up into freshwater streams as their more abundant counterparts do. Despite its species name, Kuhlia sandvicensis is not endemic to Hawaiʻi, but xenuria is - this mix-up a result of the earlier taxonomic confusion. No matter to the fishermen though, who know theyʻre both ʻono loa.
* ASPECTS OF THE BEHAVIORAL ECOLOGY, LIFE HISTORY, GENETICS, AND MORPHOLOGY OF THE HAWAIIAN KUHLIID FISHES by Lori Keene Benson, 2002.
Visit any of the many tidepools here in Hawaii and you will likely meet up with Istiblennius zebra, known locally as pāoʻo, zebra rockskipper, zebra blenny, or jumping jack. Their color can range from blackish to greyish brown with vertical banding, hence the zebra name.
They are a bit comical looking, with a blunt, froggy mouth and froggy eyes, and an upright flap atop their head. And speaking of froggy, these guys can hop! Being tidepool residents, pāoʻo are quite wary of predators, and will dart under a rock, or leap on over to a neighboring tidepool for a quick get-away. They can slither their long, laterally compressed bodies like an eel, and seem to favor curling their tails around like a "J" when resting. Similar to other blennioids, they have a long dorsal fin, and are scaleless. Pāoʻo spend much of their time resting or feeding on the bottom, in search of detritus or algae. Females lay eggs, which they cement into small nooks or under ledges; the male guards the cluster until the fry emerge. The little ones take to the sea for a time, eventually returning to the pools.
As I was hiking out to Ka'ena Point this morning for the The Sanctuary Ocean Humpback Whale Count, I came across this rough rider in one of the tidepools. It's ha 'uke 'uke, a.k.a. helmet or shingle urchin. Unlike their sharp and spiky brethren, this urchin's spines are modified into flattened shingles or tiles that create a beautiful, if briny mosaic, nicely accented by a "skirt" of flattened spines. The skirt spines are moveable, and underneath are lots and lots of tube feet. These features combine to give them the ability to hang tight in the full-contact wave impact zone where they forage for coralline algae (Porolithon), encrusting, rock-like algae that continue the reef building when corals reach sea level, and become to fragile to handle the pounding surf. Ha 'uke 'uke can get baseball-sized, and their yellow roe is considered onolicious to Hawaiians past and present.
Seeing as these creatures are soft and slow, and without the spiny protection of their cousins, you might think they are easy pickings, but sea cucumbers have a arsenal of defenses. Their squishable bodies allow them to tuck under rocks and in small crevices. Some simply taste bad due to noxious chemicals in their skin. But here's something unique: some cukes expel Cuvierian tubules from their anus - sticky threads that entangle predators, and may be accompanied by the release of a toxin called holothurin. Take that! And just in case, some sea cukes can also eviscerate, which essentially means that they can expel some of their insides, sneak away, and then spend a good portion of time regenerating.
Scuttling along in tide pools throughout Hawaii are some familiar critters that really deserve a second look. They are hermit crabs, probably one of the creatures most responsible for getting children interested in the natural world. Today's post features a few from the genus Calcinus that inhabit tide pools and shallow reefs, though other hermit crabs live in deeper waters. With a closer look, you'll notice that the rainbow of colors on their eyes, legs, and claws that help to identify them. What you don't see, of course, is the soft and vulnerable abdomen that is modified to fit into the protection of a discarded shell, with back legs specially designed to grip and hook. As hermit crabs grow, they need to find a suitably sized new home. Empty shells are a valuable resource to hermit crabs, and a prospective home is thoroughly explored to see if the fit is right. The crabs try it on for size, and take up residency if everything is snug. If, for whatever reason, they begin to outgrow a shell but are unable to find a new one that fits well, they are more vulnerable to predation from any number of enemies, including crabs, reef fish, and octopi. They themselves are omnivores, and are happy munching on the abundant algae in the tide pools, as well as whatever tidbits float by, including debris. So next time you visit a tide pool, take a closer look at these colorful little guys, but leave any empty shells you may see. Housing is in short supply.
Though you may not realize it, tucked away in the nooks and crannies of Hawaii's reefs are more than forty species of moray eels. If you're lucky, you'll see the snout of one as it guards its den, oftentimes with its mouth agape. This promotes water circulation over its gills, which are but a small hole on the side. These sly and shy bony fish are some of the reef's top predators, slithering out of their hiding places to hunt at night, though some species, such as the snowflake moray, will venture out during the day. Without pelvic and pectoral fins, locomotion is achieved by a serpentine undulation of their bodies. Some morays eat fish, octopi and the like, others prefer crustaceans, and their anatomies are adapted for this variation in diet. The fish-eating morays have a longer snout and backward curving teeth; the crustacean-eaters have a blunter snout and nubbier teeth better suited for crunching and munching.
While eels have a fearsome reputation, they are not generally aggressive unless you disturb them in their den, and if bitten by a fish-eating moray, the wound can be serious due to the curve of the teeth. If you do any spearfishing, though, you may encounter one of the larger and more common eels, the Yellowmargin moray, Gymnothorax flavimarginatus. The Waikiki Aquarium's fact sheet on this eel, known as the puhi-paka, or fierce eel, reports that they show a particular interest in injured fish, and have been known to investigate the goings-on of spearfishermen.
welcomes you to visit with the all the wonderful flora and fauna that we share this lovely aina with.