Halfmoon picassofish facts for kids
Quick facts for kids Halfmoon picassofish |
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The Rhinecanthus lunula, also known as the halfmoon picassofish, is a type of balistid triggerfish. Scientists John E. Randall and Roger C. Steene first described this fish in 1983. It belongs to a group of triggerfish found in the Indo-Pacific ocean, called Rhinecanthus.
What Does It Look Like?
The halfmoon picassofish has a unique look. The first fish ever described was about 180 millimeters (about 7 inches) long. Other fish of this type have been found ranging from 45.6 to 218 millimeters (about 1.8 to 8.6 inches) long.
You can tell this fish apart from other Rhinecanthus species by its colors and fin rays. It usually has 26 soft rays on its top fin, and 22 to 24 soft rays on its bottom fin. It also has 14 rays on its side fins.
This fish has a wide, black bar near its tail. Just in front of this bar is a curved black line. This line looks like a crescent moon, which is why it's called "lunula." "Lunula" is a Latin word for crescent. An orange-yellow band stretches from its upper lip, across its head, to its side fin. The halfmoon picassofish also has a long snout and a body that is a bit flat on the sides.
Young Fish vs. Adults
Young halfmoon picassofish look different from adults. For example, a young fish's tail fin is round. As it grows, the tail becomes slightly notched. Young fish also lack some of the bright colors seen in adults. They don't have a dark area on their belly. The black bars below their eyes are not fully formed. The black crescent near the tail, which gives the fish its name, is also missing in young ones.
However, young fish have two yellow stripes that adults do not. Also, the space between the eyes is slightly curved inward in young fish. In adults, this space becomes slightly curved outward.
Where Does It Live?
The halfmoon picassofish is a rare fish. It lives in a small area of the ocean. When it was first discovered, it was only known to live from the Pitcairn Islands to Queensland, Australia. The first specimen was found near the Society Islands of Tahiti. Young fish were found near Queensland, Australia.
Most sightings of this fish are in this same area. However, scuba divers once reported seeing one in Egypt. But this fish might have been a different type of triggerfish. Other Rhinecanthus species, like the lagoon triggerfish and reef triggerfish, are known to live in Africa.
Rhinecanthus lunula usually lives in the outer parts of coral reefs. They are found at depths of 10 meters (about 33 feet) or deeper. We don't know the deepest they can live. But other triggerfish can live as deep as 50 meters (about 164 feet). Young fish might live in different places than adults. For example, young lagoon triggerfish often live near beaches. Adult lagoon triggerfish prefer barrier reefs. Where a triggerfish lives can also depend on what it eats.
Reproduction
Triggerfish, including the halfmoon picassofish, have a special way of mating. A male triggerfish often has several female mates. This is called a harem mating system.
