Novaculichthys
A single-species wrasse known for moving stones to find prey.
Novaculichthys is a genus of wrasse containing the single species Novaculichthys taeniourus, known commonly as the rockmover wrasse, carpet wrasse, dragon wrasse, bar-cheeked wrasse, olive-scribbled wrasse, or reindeer wrasse. It is notable for its behavior of upending small stones and reef fragments in search of prey, which gives it the common name 'rockmover wrasse.' The genus name derives from Latin Novacula (razor) and Greek ikhthús (fish), while the specific name taeniourus combines Greek tainía (ribbon) and oura (tail).
Quick Facts
- Taxon
- Novaculichthys taeniourus
Facts from the source article.
Lore & Background
The rockmover wrasse is a colorful fish with an oblong, laterally compressed body and a wedge-shaped head. Its head is scaleless except for two scales on the upper part of the gill coverings and an almost vertical row of small scales behind each eye. Juveniles and adults have markedly different appearances: juveniles have long, extended first two dorsal fin spines that droop over the forehead like a cowlick, while adults lose these elongated rays. Adult fish have 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, a wide vertical white bar on the base of the caudal fin, and black posterior caudal fin and pelvic fins. The difference is so striking that adults are called 'rockmover wrasse' and juveniles 'dragon wrasse.' Juveniles resemble algae and mimic the movements of detached, drifting seaweed by swaying back and forth in currents.
Reader's Guide
The rockmover wrasse is the only known member of its genus, Novaculichthys, making it taxonomically significant. Its behavior of turning or shifting large pieces of debris or rubble with its mouth or snout to reveal prey is a defining characteristic, often performed by one fish of a pair while the other quickly grabs the exposed food. Juveniles do not usually work in pairs, doing all the work themselves. Adults are highly territorial and pairs often protect large areas of reef. In Japan, rockmover wrasses have been recorded constructing sleeping mounds made of coral fragments and sand, topping the mound with up to 70 pieces of round or flattened coral fragments, primarily faviid corals. When moving coral fragments too large to pick, the fish drags them while swimming backwards. The species feeds on benthic invertebrates including molluscs, crabs, and polychaete worms. Facing danger, these wrasses quickly dive into the sand for protection. Little is known about reproduction, but like other wrasses they probably are able to change sex and are pelagic spawners.
Did You Know?
- Juveniles are called 'dragon wrasse' due to their long, drooping dorsal fin spines that form a cowlick.
- In Japan, rockmover wrasses construct sleeping mounds of sand topped with up to 70 coral fragments.
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