Rockmover Wrasse

Novaculichthys taeniourus, commonly referred to as the rockmover wrasse, exhibits a variety of nomenclature including the carpet wrasse, dragon wrasse, bar-cheeked wrasse, olive-scribbled wrasse, and reindeer wrasse. This species predominantly inhabits coral reefs and lagoons within the Indo-Pacific region, extending from the Gulf of 🇺🇸 California to 🇵🇦 Panama, including islands in the tropical 🌊 Pacific Ocean such as Hawaii (🇺🇸 United States), as well as the 🇵🇭 Philippines, 🇮🇩 Indonesia, 🇦🇺 Australia, and the 🌊 Indian Ocean along the east coast of Africa. The moniker "rockmover wrasse" is derived from their unique behavior of overturning small stones and reef fragments to locate prey. This particular species stands as the sole representative of its genus.

The genus name "Novaculichthys" combines the Latin term "Novacula," meaning razor, with the Greek word "ikhthús," meaning fish. The specific name "taeniourus" derives from the Greek "tainía," signifying ribbon, and "oura," meaning tail.

The rockmover wrasse is characterized by vibrant coloration and measures approximately 27–30 cm (11–12 in) in length. It possesses an oblong, laterally compressed body complemented by a wedge-shaped head. Notably, the head lacks scales except for two positioned on the upper part of the gill coverings and an almost vertical row of small scales behind each eye. Distinct differences are observed between juvenile and adult appearances. Juvenile fish feature elongated first two dorsal fin spines that droop over the forehead forming a "cowlick." As the fish mature, these elongated rays are lost. Adults exhibit a dark greenish-brown body with an elongated white spot on each scale, a gray-blue head with brown lines radiating from the eyes, two black spots in front of the dorsal fin, and a wide vertical white bar on the caudal fin's base. The posterior part of the caudal fin and the pelvic fins are black. Juveniles in Hawaii (🇺🇸 United States) are typically green, whereas those in the western Pacific display a burgundy to brownish coloration, both with white spotting. The stark contrast between juvenile and adult appearances has led to the use of "rockmover wrasse" for adults and "dragon wrasse" for juveniles.

Adult rockmover wrasses occupy shallow, semi-exposed reef flats, lagoons, and seaward reefs at depths ranging from 14–25 m (46–82 ft). They show a preference for hard-bottomed grassy areas embellished with mixed sand and rubble and subject to mild surge exposure. Contrarily, juveniles favor shallow zones on rubble amidst large patch reefs or protected open patches on reef crests.

While reproductive behaviors of this species remain largely uncharted, it is likely, akin to other wrasses, that they possess the ability to change sex and engage in pelagic spawning, dispersing eggs and sperm into the water column.

Exhibiting strong territorial instincts, adult pairs diligently safeguard expansive reef territories. Their diet comprises benthic invertebrates, including molluscs, crabs, and polychaete worms. Typical foraging involves one individual manipulating large debris or rubble, utilizing its mouth or snout to dislodge it, subsequently exposing prey for the opportunistic partner to swiftly consume. In contrast, juveniles typically forage independently. In the presence of threats, these fishes possess a rapid response mechanism whereby they burrow into the sand for shielded protection. The juvenile stage mimics algae, replicating the rhythmic sway of detached, drifting seaweed within water currents.

Their distribution spans across tropical 🌊 Indian Ocean and 🌊 Pacific Ocean reefs and lagoons, underscoring their ecological adaptation and significance.