Humphead wrasse

The humphead wrasse (Cheilinus undulatus) is a species of wrasse mainly found on coral reefs in the Indo-Pacific region. It is also known as the Māori wrasse, Napoleon wrasse, Napoleon fish, Napoleonfish, so mei 蘇眉 (Cantonese), mameng (Filipino), and merer in the Pohnpeian language of the Caroline Islands. The humphead wrasses can be located with in the east coast of Africa and Red Sea's ocean, as well as in the Indian Ocean to the Pacific Ocean. Juvenile and adult humphead wrasses are found in different ranges. Juveniles are usually found in shallow, sandy ranges that are bordering coral reef waters, while adults are mostly found in offshore and deeper areas of the coral reefs, typically in outer-reef slopes and channels, but can also be found in lagoons. Humphead wrasses are found in small groups or larger combinations within their habitat. The humphead wrasse is the largest living member of the family Labridae. Males are typically larger than females and are capable of reaching lengths of up to 2 meters from tip to tail and weighing up to 180 kg, but the average length is generally a little less than 1 meter. Females rarely grow larger than one meter in length. This species of fish can be easily identified by its large size, thick lips, two black lines behind its eyes, and the hump that appears on the forehead of larger adults. The color of the humphead wrasse can vary between a dull blue-green to more vibrant shades of green and purplish-blue. This particular reef fish prefers to live singly but adults are occasionally observed moving in small groups. The humphead wrasse is long-lived, but has a very slow breeding rate. Individuals become sexually mature at four to six years, and females are known to live for around 50 years, whereas males live a slightly shorter 45 years. Humphead wrasses are protogynous hermaphrodites, with some members of the population becoming male at about 9 years old. The factors that control the timing of sex change are not yet known. Adult humphead wrasse lay around 20 eggs at a time, also taking 20-30 days to hatch. Adults move to the down-current end of the reef and form local spawning aggregations (they concentrate to spawn) at certain times of the year. Humphead wrasses likely do not travel very far for their spawning aggregations. The humphead wrasse pelagic eggs and larvae ultimately settle on or near coral reef habitats. Eggs are 0.65 mm in diameter and spherical, with no pigment. Being very opportunistic predators, C. undulatus preys primarily on invertebrates such as mollusks (particularly gastropods and pelecypods), echinoids, crustaceans, annelids) and fish. Half of echinoids and most pelecypods hide under the sand, leaving one of two options: the humphead wrasses rely on fish excavators like stingrays, or they themselves excavate by ejecting water and nosing around to look for prey. Often, these wrasses, like many other Red Sea wrasses, crack sea urchins (echinoids) by carrying them to a rock in their mouths and striking them against a rock by moving their heads in sideways, brisk movements. They sometimes engage in cooperative hunting with the Roving coral grouper. Adults are commonly found on steep coral reef slopes, channel slopes, and lagoon reefs in water 3 to 330 ft (0.91 to 100.58 m) deep. This species actively selects branching hard and soft corals and seagrasses at settlement. Juveniles tend to prefer a more cryptic existence in areas of dense branching corals, bushy macroalgae, or seagrasses, while larger individuals and adults prefer to occupy limited home ranges in more open habitat on the edges of reefs, channels, and reef passes. The species is most often observed in solitary male-female pairs, or groups of two to seven individuals.