The wrasses are a family, Labridae, of marine ray-finned fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 81 genera, which are divided into eight Subfamily.
They are typically small, most of them less than long, although the largest, the humphead wrasse, can measure up to . They are efficient carnivores, feeding on a wide range of small . Many smaller wrasses follow the feeding trails of larger fish, picking up invertebrates disturbed by their passing.
Etymology
The word "wrasse" comes from the
Cornish language word wragh, a
lenition form of gwragh, meaning an old woman or hag, via
Cornish dialect wrath. It is related to the
Welsh language gwrach and
Breton language gwrac'h.
Taxonomy
Parrotfish were traditionally regarded as comprising their own family (Scaridae), but are now often treated as a subfamily (Scarinae) or tribe (Scarini) of the wrasses (Labridae), being nested deep within the wrasse phylogenetic tree.
The
Odacidae wrasses, traditionally classified as forming their own family, were found nested deep within the wrasse tribe
Hypsigenyini, and most closely related to the
Choerodon.
Genera
The following classification is based on
Eschmeyer's Catalog of Fishes:
| +
!Subfamily
!Genera |
| Hypsigenyinae | Blue groper, Natal wrasse, Bodianus, Choerodon, Decodon, Hogfish, Polylepion, Pseudodax, Terelabrus, Haletta, Heteroscarus, Neoodax, Odax, Parodax, Olisthops, Sheardichthys, Siphonognathus. |
| Cirrhilabrinae | Cirrhilabrus, Paracheilinus, Pseudocheilinops, Pseudocheilinus, Pteragogus. |
| Labrinae | Acantholabrus, Centrolabrus, Ctenolabrus, Labrus, Lappanella, Symphodus, Tautog, Cunner |
| Cheilininae | Cheilinus, Epibulus, Oxycheilinus, Wetmorella. |
| Scarinae | Bolbometopon, Calotomus, Cetoscarus, Chlorurus, Cryptotomus, Hipposcarus, Leptoscarus, Nicholsina, Scarus, Sparisoma. |
| Xyrichtyinae | Ammolabrus, Cigar wrasse, Cymolutes, Iniistius, Novaculichthys, Novaculoides, Novaculops, Xyrichtys |
| Pseudolabrinae | Austrolabrus, Doratonotus, Dotalabrus, Eupetrichthys, Malapterus, Notolabrus, Pictilabrus, Pseudolabrus, Suezichthys |
| Julidinae | Anampses, Coris, Diproctacanthus, Frontilabrus, Gomphosus, Halichoeres, Hemigymnus, Hologymnosus, Tubelip wrasse, Labroides, Labropsis, Four-line wrasse, Leptojulis, Macropharyngodon, Minute wrasse, Ophthalmolepis, Parajulis, Pseudocoris, Pseudojuloides, Stethojulis, Thalassoma, Finspot wrasse. |
The following fossil genera are also known, lacking a proper tribal placement:
Fossil wrasses date to the Ypresian of Monte Bolca, Italy. Among these is Phyllopharyngodon, which can uniquely be placed in the extant subfamily Hypsigenyini.
Description
Wrasses have
Fish jaw, usually with separate jaw teeth that jut outwards.
Many species can be readily recognized by their thick lips, the inside of which is sometimes curiously folded, a peculiarity which gave rise to the German name of "lip-fishes" (Lippfische),
and the Dutch name of lipvissen. The
dorsal fin has 8 to 21 spines and 6 to 21
soft rays, usually running most of the length of the back. Wrasses are sexually dimorphic. Many species are capable of changing sex. Juveniles are a mix of males and females (known as initial-phase individuals), but the largest adults become territory-holding (terminal-phase) males.
The wrasses have become a primary study species in fish-feeding biomechanics due to their jaw structures. The nasal and Mandible 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 four 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.
Distribution and habitat
Most wrasses inhabit the tropical and subtropical waters of the Atlantic, Indian, and Pacific Oceans, though some species live in temperate waters: the
Ballan wrasse is found as far north as Norway. Wrasses are usually found in shallow-water habitats such as
and rocky shores, where they live close to the substrate.
Reproductive behavior
Most labrids are
Dichogamy within a haremic
mating system.
[
][
] A good example of this reproductive behavior is seen in the California sheephead. Hermaphroditism allows for complex mating systems. Labroids exhibit three different mating systems:
Bachelor group, lek-like, and promiscuous.
[
] Group spawning and pair spawning occur within mating systems. The type of spawning that occurs depends on male body size.
Labroids typically exhibit broadcast spawning, releasing high numbers of
eggs, which are broadcast by
Tide currents; adult labroids have no interaction with offspring.
[
] Wrasses of a particular subgroup of the family Labridae, Labrini, do not exhibit broadcast spawning.
Sex change in wrasses is generally female-to-male, but experimental conditions have allowed for male-to-female sex change. Placing two male Labroides dimidiatus wrasses in the same tank results in the smaller of the two becoming female again.[
] Additionally, while the individual to change sex is generally the largest female,[
] evidence also exists of the largest female instead "choosing" to remain female in situations in which she can maximize her evolutionary fitness by refraining from changing sex.[
]
Broodcare behavior of the tribe
The subfamily Labrinae arose from a basal split within family Labridae during the
Eocene.
[
] Subgroup Labrinae is composed of eight genera, wherein 15 of 23 species exhibit broodcare behavior,
which ranges from simple to complex parental care of spawn; males build algae nests or crude cavities, ventilate eggs, and defend nests against
conspecific males and predators.
In species that express this behavior, eggs cannot survive without parental care.
[
] Species of
Symphodus, Centrolabrus, and
Labrus genera exhibit broodcare behavior.
Sexual developmental systems
Wrasses exhibit three types of sexual development, depending on the species. Sex in this context refers to functional sex, ie the individual's role when mating. Some species show functional
gonochorism, meaning that they are born functionally either male or female, and remain so for their entire life; there is no sex change. Meanwhile, functionally hermaphroditic species exhibit sex change, and are protogynous, meaning that individuals that are functionally female can become functionally male. These protogynous species are either monandric (all individuals are born functionally female, but can become functionally male) or diandric (individuals can be born either female or male, and individuals that are born female can become male).
Evolutionarily, wrasse lineages trend towards developing monandry.
Potential tool use
Many species of wrasses have been recorded using large rocks or hard coral as "anvils", upon which they smash open hard-shelled prey items. At least some of these species can remember to use a particular rock or coral repeatedly for this purpose.
This behaviour usually involves invertebrate prey such as clams, sea urchins, and crabs, but on one occasion, a
blue tuskfish was filmed smashing a young green sea turtle on an anvil.
Twenty-one species of eight genera have been documented exhibiting this behaviour, including Choerodon ( C. anchorago, Blue tuskfish, C. graphicus, C. schoenleinii), Coris ( Clown coris, Coris bulbifrons, C. julis, C. sandeyeri), Cheilinus ( C. fasciatus, Broomtail wrasse, C. trilobatus), Thalassoma ( Sixbar wrasse, T. jansenii, Moon wrasse, T. lutescens, Ornate wrasse), Symphodus ( Axillary wrasse), Halichoeres ( H. garnoti, H. hortulanus), Bodianus ( B. pulcher), and Pseudolabrus ( Orange wrasse).
Cleaner wrasse
Cleaner wrasses are the best-known of the
cleaner fish. They live in a cleaning symbiosis with larger, often predatory, fish, grooming them and benefiting by consuming what they remove. "Client" fish congregate at wrasse "
" and wait for the cleaner fish to remove
gnathiidae parasites, the cleaners even swimming into their open mouths and gill cavities to do so.
[ "The Fish That Makes Other Fish Smarter" by Ed Yong, The Atlantic, March 7, 2018]
Cleaner wrasses are best known for feeding on dead tissue, scales, and , 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.[Trivers, R. L. 1971]
In a 2019 study, cleaner wrasses passed the mirror test, the first fish to do so.
Significance to humans
In the Western Atlantic coastal region of North America, the most common food species for indigenous humans was the
tautog, a species of wrasse.
Wrasses today are commonly found in both public and home
Aquarium. Some species are small enough to be considered
reef safe. They may also be employed as cleaner fish to combat
Sea lice infestations in salmon farms.
Commercial fish farming of cleaner wrasse for sea-lice pest control in commercial salmon farming has developed in Scotland
as lice busters, with apparent commercial benefit and viability.
Parasites
As all fish, labrids are the hosts of a number of parasites. A list of 338 parasite taxa from 127 labrid fish species was provided by Muñoz and Diaz in 2015.
[Muñoz G., Diaz P.E. 2015: Checklist of parasites of labrid fishes (Pisces: Labridae). Viña del Mar, Chile. PDF. ] An example is the
nematode Huffmanela ossicola.
Gallery
File:Humphead wrasse melb aquarium.jpg|Humphead wrasse, Cheilinus undulatus, Melbourne Aquarium
File:Coris gaimard and Labroides phthirophagus.JPG|A yellowtail coris wrasse, Coris gaimard, is being cleaned by Labroides phthirophagus in Hawaii.
File:Bird Wrasse.jpg|Bird wrasse, Gomphosus varius, Kona (Hawaii)
File:Gomphosus.jpg| Gomphosus varius
File:Birdmouth wrasse.jpg| Gomphosus caeruleus swimming with a yellow goatfish
File:Bluhead Wrasse.jpg|Bluehead wrasse, Belize Barrier Reef
File:Clown wrasse coris aygula.JPG|Clown wrasse, Coris aygula, Red Sea
File:Anampses cuvieri.jpg|Pearl wrasse, Anampses cuvieri, Hawaii
File:Ladim u0.gif|Bluestreak wrasse, Labroides dimidiatus
File:Six-line wrasse.jpg|Six-line wrasse , Pseudocheilinus hexataenia
File:A history of Scandinavian fishes (9661319663).jpg|Cuckoo wrasse and corkwing wrasse by Wilhelm von Wright
File:Christmas Wrasse, Island of Hawai'i, Hawaii, USA imported from iNaturalist photo 63881659.jpg|Several wrasse species, including Christmas wrasse, ember parrotfish, and Scarus psittacus
External links
