No discussion of coral reefs can be complete without a survey of the back-boned creatures known as the vertebrates. The most important of these are the fishes. Members of the Phylum Chordata, the cartilaginous sharks and rays and the more advanced bony fishes both possess a dorsal nerve cord housed within a hollow vertebral column. All fish possess gills for breathing and fins for locomotion, although some species have extremely reduced fins. The 450 or so species of fish found in Hawaiian waters occur in a bewildering variety of forms and colors and present a unique example of an isolated marine community. Creatures common in Hawaiian waters are many times rare or unknown in other parts of the Pacific Ocean. Butterfly fish, wrasses, and moray eels are prime examples of this rule. Of the total number of fish species found in the Hawaiian reef ecosystem, nearly ⅓ of them are found nowhere else in the world.
A multitude of beautiful and distinctive forms can be found in these coral reef communities and the surrounding waters. The spectacular Manta Ray (Manta alfredi) is an occasional visitor to the islands while the Whitetip Reef Shark (Triaenodon obesus) and the dangerous Grey Reef Shark (Carcharhinus amblyrhynchos) are residents of the reef. At least 38 species of moray eel occur in Hawaiian waters. Called "pūhi" by the local Hawaiians, moray eels are most often seen with their heads protruding from crevasses in the reef. The beautifully-spotted Whitemouth Moray Eel (Gymnothorax meleagris) is frequently seen in just such a pose. The elegant Snowflake Moray Eel (Echidna nebulosa) feeds on hard-shelled invertebrates rather than fish while the stunningly beautiful but ferocious Dragon Moray Eel (Enchelycore pardalis) is one of the most aggressive fish-eating eels in the world.
Some truly bizarre and interesting forms occur in these waters. Heading the list is the wonderfully camouflaged ambush predator known as Commerson's Frogfish (Antennarius commersoni). Barely able to swim, these amazing creatures rely on their extraordinary camouflage to capture prey.
Equally bizarre, the Flying Gurnard (Dactyloptena orientalis) uses its pelvic fins for locomotion and its large, wing-like pectoral fins for camouflage and display. As it turns out, most ambush predators are highly camouflaged, lying motionless on the reef or sea bottom and relying on their ability to remain undetected by their prey.
Commerson's Frogfish employs this method of hunting as do the scorpionfishes. A number of species of scorpionfish occur in Hawaiian waters, all of them sporting sharp, poisonous spines.
The Devil Scorpionfish (Scorpaenopsis diabolus) is nearly invisible against the mottled gray surface of the reef, while the highly-specialized Leaf Scorpionfish (Taenianotus triacanthus) mimics the rhythmic swaying motion of seaweed.