Hawaiian Reef Fauna — The Invertebrates continued

The most advanced mollusks and indeed the most intelligent invertebrates in the animal kingdom are the squids, cuttlefish, and octopi. Collectively known as the cephalopods, these amazing creatures are fairly common in Hawaiian waters, where at least 76 species have been identified. A number of interesting species occur here including Hawaii's most common diurnal octopus, the aptly named Day Octopus (Octopus cyanea), the mildly venomous Ornate Octopus (Callistoctopus ornatus), and the Bigfin Squid (Sepioteuthis lessoniana), known to local Hawaiians as the "mūhe'e".

Arthropods, and especially crustaceans, are well-represented in the coral reef communities of Hawaii. Nearly 1000 species of crustaceans inhabit the waters surrounding the islands. This highly successful group includes the barnacles, shrimps, crabs, and lobsters, plus a host of lesser known creatures like amphipods and isopods. Barnacles are benthic sessile organisms that resemble mollusks, but are much more advanced. Many of the 50 or so species that inhabit Hawaiian waters are introduced rather than endemic. These include Hawaii's largest species, Hembel's Rock Barnacle (Euraphia hembeli) and the common intertidal species known as Proteus' Rock Barnacle (Chthamalus proteus).

Seventeen species of mantis shrimp have been recorded from Hawaiian waters. Among the most intelligent invertebrates in the animal kingdom, mantis shrimp are all bottom-dwelling predators that utilize either a spear-like apparatus or a spring-loaded, "smashing" pair of arms to capture their prey. In either case, these small invertebrates can be dangerous and are capable of injuring any unwary diver who inadvertently disturbs them. Local fishermen refer to the stabbing species as "thumb-splitters". The most common species in Hawaii is probably the Ciliated Mantis Shrimp (Pseudosquilla ciliata) but a number of other interesting mantids occur here including the dangerous Giant Mantis Shrimp (Lysiosquillina maculata) and the unusual "smashing" species known as the Urchin-Tail Mantis Shrimp (Echinosquilla guerinii).

The decapod shrimps are well-represented in the reef communities and shallow waters surrounding the islands of Hawaii. About 190 species occur here including some truly fascinating and bizarre forms. Many of them form symbiotic relationships with other invertebrate species. The Margined Shrimp (Melicertus marginatus) is the largest shallow-water species in Hawaii, growing up to 8 inches in length. Hiding in the sand during the day and schooling in shallow, protected bays at night, the species is known to local Hawaiians as the "ōpae lōlō". Coral-dwelling shrimps include some of the most colorful and distinctive shrimp species known to science. In Hawaii, the strikingly-marked red and white Banded Coral Shrimp (Stenopus hispidis) is the most frequently encountered member of this group. A host of other interesting forms occur here including the flamboyant Harlequin Shrimp (Hymenocera picta), the Petroglyph Shrimp (Alpheus deuteropus) which is never seen but leaves its mark on every reef structure in the Indo-Pacific, the bizarre Marbled Shrimp (Saron marmoratus), the industrious White-Stripe Cleaner Shrimp (Lysmata amboinensis), and those lovers of Finger Coral, the Starry Hinge-Beak Shrimp (Cinetorhynchus hawaiiensis).

Some 17 species of lobsters inhabit the waters surrounding the Hawaiian Island chain. Those that frequent the reefs are generally small in size and possess claws. They also tend to be brightly colored and strictly nocturnal, hiding in caves and crevasses during the day. The Red Reef Lobster (Enoplometopus occidentalis) is just such an example, as are the Bullseye Reef Lobster (Hoplometopus holthuisi) and the beautiful, spotted creature known as Debelius' Reef Lobster (Enoplometopus debelius).

Only 4 species of spiny lobster inhabit the Hawaiian reef system. Like the reef lobsters, spiny lobsters are nocturnal, hiding in caves and openings in the reef by day, and foraging at night. But unlike them, they have no claws. Instead, their robust, forward-pointing spines are used for protection. The endemic Banded Spiny Lobster (Panuliris marginatus) is an important commercial species as is the Tufted Spiny Lobster (Panuliris penicillatus).

The slipper lobsters have distinctive flat carapaces and shovel-shaped antennae. They are sometimes called "shovel-nosed" lobsters and their Hawaiian name, "ula-pāpapa", means "flat lobster". As a group, they possess heavy, well-camouflaged carapaces that blend in well with the hard, rocky substrates that they inhabit. The Hawaiian species, which include the Sculptured Slipper Lobster (Parribacus antarcticus) and the large, heavily armored Ridgeback Slipper Lobster (Scyllarides haanii), are protected by law.

Hermit crabs are well-represented in the waters surrounding the Hawaiian Island chain. Over 40 species have been identified here, including some truly unusual forms like the giant Hairy Yellow Hermit Crab (Aniculus maximus), the even larger White-Spotted Hermit Crab (Dardanus megistos), and the unusual Cone Shell Hermit Crab (Ciliopagurus strigatus) with its colorful red and orange banded legs and striking, white carapace.

True crabs are also well-represented here with nearly 200 species identified and described. They occur in a variety of forms and colors and occupy nearly every part of the Hawaiian reef ecosystem. Swimming crabs, elbow crabs, spider crabs, sponge crabs, box crabs, stone crabs, fiddler crabs, rock crabs, ghost crabs, and coral guard crabs are all found here! Some truly beautiful and bizarre forms inhabit these waters including the flamboyant, coral-loving Red

Spotted Guard Crab (Trapezia tigrina), the largest sponge crab on Earth, the Sleepy Sponge Crab (Dromia dormia), the Thin-Shelled Rock Crab (Grapsus tenvicrustatus) which is sometimes referred to as the "Sally Lightfoot Crab", the bizarre, anemone-carrying Teddy Bear Crab (Polydectus cupulifer), the beautiful, magenta-colored Strawberry Crab (Neoliomera pubescens), the endemic stony crab known as the Knotted Liomera (Liomera supernodosa), the large, gaudy Seven-Eleven Crab (Carpilius maculatus), the Common Box Crab (Calappa hepatica) with its distinctive, tubercle-covered carapace, the wonderfully camouflaged King Kong Elbow Crab (Daldorfia rathbunae), the beautiful Rainbow Swimming Crab (Charybdis erythrodactyla), and Hawaii's largest swimming crab, the edible Samoan Crab (Scylla serrata).

The echinoderms or "spiny-skinned" animals possess a hard, calcareous endoskeleton that displays a unique, 5-way pentameral symmetry. This odd group of invertebrates includes the sea stars, sand dollars, sea urchins, sea lilies, and sea cucumbers. Nearly 300 species occur in Hawaiian waters including a number of unique and interesting forms. Of the 50 or so sea cucumber species found here, the Lion's Paw Sea Cucumber (Euapta godeffroyi) may be the largest, attaining lengths of up to 4 feet! Other interesting forms include the endemic Hawaiian Spiky Sea Cucumber (Stichopus species 1) and the tubule-secreting Impatient Sea Cucumber (Holothuria impatiens). These sticky, white tubules are toxic in some species.