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Seaweek 2010: Oceans of Life - ours to explore; ours to restore


The wrasses are a family 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

• Wrasse are found in 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.

• Wrasses have protractile mouths, 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, The dorsal fin has 8–21 spines and 6–21 soft rays, usually running most of the length of the back.

• Wrasse are typically brightly coloured and sexually dimorphic.

Cleaner Wrasse

• Some wrasses are widely known for their role as symbiotic fish, other fish will congregate at wrasse cleaning stations and wait for wrasses to swim into their open mouths and gill cavities to have gnathiid parasites removed.

• The cleaner wrasses are best known for feeding on dead tissue and scales and ectoparasites, although they are also known to 'cheat' through the removal of healthy tissue and mucus, which is costly for the client fish to produce. They eat parasites and dead tissue off larger fishes' skin in a mutualist relationship that provides food and protection for the wrasse, and considerable health benefits for the other fish.

• 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 the removal of parasites from the predator fish is more important for the survival of the predator than the short-term gain of eating the cleaner.

• At the cleaning stations, the bigger fishes recognise the cleaner fish by looking at their color and movement patterns, and subsequently stiffen to be cleaned.

• All cleaner wrasses start their lives as females. In a group of 6-8 cleaner wrasses there is but one male, the rest are females or juveniles. The strongest female changes its sex when the male dies, an occurrence known as sequential hermaphroditism.

• Cleaner wrasses sleep in crevices between rocks or corals, covered in a slime layer that is secreted at dusk. In the morning these can be seen floating on the surface.

Humphead Wrasse

• The humphead wrasse is a wrasse that is mainly found in coral reefs in the Indo-Pacific region. It is also known as the Maori wrasse it is the largest living member of the family Labridae, with males reaching 8.2 feet (2.5 m) in length, while females rarely exceed about 3 feet (1 m). It has thick, fleshy lips and a hump that forms on its head above the eyes, becoming more prominent as the fish ages.

• Males range from a bright electric blue to green, a purplish blue, or a relatively dull blue/green. Juveniles and females are red-orange above, and red-orange to white below.

• Adults are commonly found on steep coral reef slopes, channel slopes, and lagoon reefs in water 3 to 330 feet (1-100 m) deep. They are very opportunistic predators preying primarily on crustaceans, mollusks - particularly gastropods- fish, echinoderms. They are one of the few predators of toxic animals such as the sea hare Aplysia and boxfish Ostraciidae and have even been reported preying on crown-of-thorns star fish. .

• Individuals become sexually mature at 5 to 7 years and females are known to live for around 30 years whereas males live a slightly shorter 25 years. Maori wrasse are protogynous hermaphrodites, with some members of the population becoming male at approximately 9 years old .The factors that control the timing of sex change are not yet known.

• Reef Check Australia identify and monitor the Humphead Wrasse. Low numbers indicate overfishing, which can imbalance the sex ratio, and further decrease numbers.

Interesting fact: Wrasse reproduce in mass spawning events, where males chase each other to try to get the most females for themselves.

Further links:

• Wikipedia:

• Wikipedia:




Checkerboard Wrasse
from GBRMPA Image Collection





The arrow points to two small Cleaner Wrasse swimming with a Painted sweetlips
from GBRMPA Image Collection







Humphead Maori wrasse
from GBRMPA Image Collection

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