wrasse

Wrasses
Moon wrasse, Thalassoma lunare, a typical wrasse
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Perciformes
Suborder:	Labroidei
Family:	Labridae Cuvier, 1816
Genera
See text.

The wrasses are a family, Labridae, of marine fish, many of which are brightly colored. The family is large and diverse, with about 500 species in 60 genera.

They are typically small fish, with most less than 20 centimetres (7.9 in) long, although the largest, the Humphead wrasse, can measure up to 2.5 metres (8.2 ft). They are efficient carnivores, feeding on a wide range of small invertebrates. Many smaller wrasses follow the feeding trails of larger fish, picking up invertebrates disturbed by their passing.^[1]

The word "wrasse" comes via Cornish from the Welsh word gwrach meaning an old woman or hag.^[2]

Distribution

Wrasses inhabit the Atlantic, Indian, and Pacific Oceans, usually in shallow water habitats such as coral reefs and rocky shores where they live close to the substrate.

Anatomy

Lips of Labrus festivus

Wrasses have protractile mouths, usually with separate jaw teeth that jut outwards.^[3] Many species can be readily recognized by their thick lips, the inside of which is sometimes curiously folded, a peculiarity which gave rise the German name of "lip-fishes" (Lippfische.)^[4] The dorsal fin has 8–21 spines and 6–21 soft rays, usually running most of the length of the back. Wrasse are sexually dimorphic. Many species are capable of changing sex. Juveniles are a mix of males and females (known as Initial Phase or IP individuals) but the largest adults become territory-holding (Terminal Phase or TP) males.^[3]

The wrasses have become a primary study species in fish-feeding biomechanics due to their jaw structure. The nasal and mandibular bones are connected at their posterior ends to the rigid neurocranium, and the superior and inferior articulations of the maxilla are joined to the anterior tips of these two bones, respectively, creating a loop of 4 rigid bones connected by moving joints. This "four-bar linkage" has the property of allowing numerous arrangements to achieve a given mechanical result (fast jaw protrusion or a forceful bite), thus decoupling morphology from function. The actual morphology of wrasses reflects this, with many lineages displaying different jaw morphology that results in the same functional output in a similar or identical ecological niche.^[3]

Cleaner wrasse

Cleaner wrasses working on dragon wrasse Novaculichthys taeniourus, Labroides sp. on a reef in Hawaii

Some wrasses are best known as symbiotic fish, similar to the actions and those ascribed to the Egyptian plover: other fish will congregate at wrasse cleaning stations and wait for wrasses to swim into their open mouths and gill cavities to remove gnathiid parasites. Cleaner wrasses are best known for feeding on dead tissue and scales and ectoparasites, although they are also known to 'cheat', consuming healthy tissue and mucus, which is energetically costly for the client fish to produce. The bluestreak cleaner wrasse, Labroides dimidiatus is one of the most common cleaners found on tropical reefs. Few cleaner wrasses have been observed being eaten by predators, possibly because parasite removal is more important for predator survival than the short-term gain of eating the cleaner.^[5]

Other wrasse species, rather than inhabiting fixed locations, make "house calls"—that is, their "clientele" is too territorial or shy to go to a cleaning station.

Significance to humans

Humans eat wrasse in many places. In the western Atlantic, the most common food species is the tautog.^{[4][dubious – discuss]} Wrasse are common in both public and home aquaria. Some species are small enough to be considered reef safe.

Gomphosus varius in Kona	Yellowtail coris wrasse, Coris gaimardi is being cleaned by Labroides phthirophagus. The picture was taken in Hawaii	Bluehead wrasse, Belize Barrier Reef	Clown wrasse, Coris aygula, Red Sea
Yellowtail wrasse, Coris gaimard, Hawaii	Pearl wrasse, Anampses cuvieri, Hawaii	Humphead wrasse, Cheilinus undulatus, Melbourne Aquarium	Bluestreak wrasse, Labroides dimidiatus
Gomphosus varius	Gomphosus caeruleus swimming with Yellow goatfish	Six-line Wrasse (Pseudocheilinus hexataenia)

Genera

References

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (November 2008)

External links

• FishBase info for Labridae
• How Fish Hire a Cleaning Service

Look up wrasse in Wiktionary, the free dictionary.

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