Moon wrasse
Encyclopedia
The moon wrasse, Thalassoma lunare, is a wrasse
of the Labridae family
found in the Indo-Pacific
oceans at depths of between 1 and 20 m. It has a tendency to stay at the coral reef
and surrounding areas. [Eyewitness Handbooks, Aquarium Fish, Dick Mills]. Moon wrasses are carnivorous and tend to prey on fish eggs and small invertebrates. These include various bristle worms, shrimp
, young crabs, brittle stars, and even the occasional urchin
.
Its length is up to 30 centimeters, although they tend to average about 25.
Juveniles are blue on the lower half of the body. They have a black spot in the middle of the dorsal fin and a black blotch on the caudal fin base. As they mature, the spot turns into a yellow crescent, hence the name. The body is green, with prominently marked scales. Coloration of the head ranges from blue to magenta, with a broken checkerboard
pattern.
Moon wrasses are active fish, said to be moving all day long. They are also territorial, nipping, chasing, and otherwise harassing fish that get in their way.
Being diurnal, wrasses have strong vision, although they also have a decent sense of smell. At night, they rest in niches often under rocks or other such structures. If needed, a moon wrasse may dig out a space under a rock by repeatedly swimming through it until it fits without struggle.
They are protogynous hermaphrodite
s, all starting off as female and changing to male, a process which, for the moon wrasse, takes only ten days. Some, but not all moon wrasses live in groups consisted of a dominant male, and a "harem" of about a dozen other wrasses, some female and some male. The alpha male is brighter colored, and at every low tide hour, he changes from green to blue, and goes into a show of attacking and nipping all the other wrasses. This is his way of showing his dominance to the rest of the males and keeping the females in check. During breeding season and before high tide, the alpha male turns completely blue, gathers up every single female, and the spawning frenzy begins. Sometimes, non-alpha males will have extra large testes, and they will ejaculate from a greater distance. [Australia, an Ecotravellers Guide, Hannah Robinson, 2004]
Moon wrasses may live up to a decade in captivity, although this is shorter in the wild. They are popular fish in the aquarium trade, due to their hardiness, bright colors, and engaging behavior. They are renounced for their ability to tolerate spikes in nitrite
, and eat bristle worms, a fish keeper's pest. Aside from this, though, moon wrasses have no commercial value. This species is a common sight in tropical waters, and is not considered to be endangered.
Wrasse
The wrasses are a family, Labridae, of marine fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 82 genera, which are divided into nine subgroups or tribes....
of the Labridae family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
found in the Indo-Pacific
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
oceans at depths of between 1 and 20 m. It has a tendency to stay at the coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
and surrounding areas. [Eyewitness Handbooks, Aquarium Fish, Dick Mills]. Moon wrasses are carnivorous and tend to prey on fish eggs and small invertebrates. These include various bristle worms, shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
, young crabs, brittle stars, and even the occasional urchin
Urchin
Urchin or urcheon is the Middle English term for "hedgehog". As such, it is applied to many things that take a similar form to a hedgehog:* Street children, homeless children who live on the street...
.
Its length is up to 30 centimeters, although they tend to average about 25.
Juveniles are blue on the lower half of the body. They have a black spot in the middle of the dorsal fin and a black blotch on the caudal fin base. As they mature, the spot turns into a yellow crescent, hence the name. The body is green, with prominently marked scales. Coloration of the head ranges from blue to magenta, with a broken checkerboard
Checkerboard
A checkerboard or chequerboard is a board of chequered pattern on which English draughts is played. It is an 8×8 board and the 64 squares are of alternating dark and light color, often red and black....
pattern.
Moon wrasses are active fish, said to be moving all day long. They are also territorial, nipping, chasing, and otherwise harassing fish that get in their way.
Being diurnal, wrasses have strong vision, although they also have a decent sense of smell. At night, they rest in niches often under rocks or other such structures. If needed, a moon wrasse may dig out a space under a rock by repeatedly swimming through it until it fits without struggle.
They are protogynous hermaphrodite
Hermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
s, all starting off as female and changing to male, a process which, for the moon wrasse, takes only ten days. Some, but not all moon wrasses live in groups consisted of a dominant male, and a "harem" of about a dozen other wrasses, some female and some male. The alpha male is brighter colored, and at every low tide hour, he changes from green to blue, and goes into a show of attacking and nipping all the other wrasses. This is his way of showing his dominance to the rest of the males and keeping the females in check. During breeding season and before high tide, the alpha male turns completely blue, gathers up every single female, and the spawning frenzy begins. Sometimes, non-alpha males will have extra large testes, and they will ejaculate from a greater distance. [Australia, an Ecotravellers Guide, Hannah Robinson, 2004]
Moon wrasses may live up to a decade in captivity, although this is shorter in the wild. They are popular fish in the aquarium trade, due to their hardiness, bright colors, and engaging behavior. They are renounced for their ability to tolerate spikes in nitrite
Nitrite
The nitrite ion has the chemical formula NO2−. The anion is symmetric with equal N-O bond lengths and a O-N-O bond angle of ca. 120°. On protonation the unstable weak acid nitrous acid is produced. Nitrite can be oxidised or reduced, with product somewhat dependent on the oxidizing/reducing agent...
, and eat bristle worms, a fish keeper's pest. Aside from this, though, moon wrasses have no commercial value. This species is a common sight in tropical waters, and is not considered to be endangered.