Jansen's wrasse facts for kids
Quick facts for kids Jansen's wrasse |
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Jansen's wrasse (Thalassoma jansenii) is a colorful fish that lives in the ocean. It belongs to a group of fish called wrasses. You can find this fish in the Indian Ocean and the Pacific Ocean. Sometimes, people keep them in home aquariums. In some parts of the Pacific, you might find a very similar fish called the black-barred wrasse instead.
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What Does Jansen's Wrasse Look Like?
Jansen's wrasse has a very striking look. When they are young, or in their "initial phase," they are mostly white. They have three bold black stripes across their body.
- The first black stripe is on the top part of their head and front body. It also has a yellow line near its gill cover.
- The second stripe goes across their back fin (called the dorsal fin) and ends near their belly.
- The third stripe covers most of their body and the back parts of their dorsal and anal fins.
As they get older, especially the males, they change. Older males, in their "terminal phase," have bright yellow colors between these black stripes. Their side fins, called pectoral fins, often have a pretty bluish color. This fish can grow to about 20 centimeters (8 inches) long. Like many fish, it has special rays in its fins. Its dorsal fin has 8 strong spines and 13 soft rays, while its anal fin has 3 spines and 11 soft rays.
Where Does Jansen's Wrasse Live?
Jansen's wrasse lives in the warm waters of the Indian Ocean and the Pacific Ocean. You can find them from the Maldives, which are islands in the Indian Ocean, all the way to Fiji in the Pacific. They also live as far north as Japan and as far south as Shark Bay in Western Australia.
How Does Jansen's Wrasse Live?
Jansen's wrasse loves to live in coral reefs. They are often found over flat areas of the reef, usually in water that is 1 to 15 meters (3 to 49 feet) deep. However, they usually don't go deeper than 12 meters (39 feet).
This fish is a carnivore, which means it eats other animals. Its diet includes small creatures that live on the ocean floor, like tiny invertebrates, and sometimes larger animals too. Jansen's wrasse is a social fish and likes to live in groups.
Like many other wrasses that live on coral reefs, they have a special way of swimming. They mostly use their pectoral fins (the ones on their sides) to push themselves through the water. This is called "labriform locomotion."
Jansen's wrasse is also a protogynous hermaphrodite. This is a fancy way of saying that they are all born as females. Some of these females can later change into males if there aren't enough males around. They have also been seen acting as cleaner fish, which means they help other, bigger fish by eating parasites off their bodies.
Why Is Jansen's Wrasse Important to Humans?
Jansen's wrasse is a popular fish for people who have home aquariums. They are collected for the aquarium trade because of their beautiful colors and interesting behavior.
Who Discovered This Fish?
Jansen's wrasse was first officially described in 1856. It was given the name Julis jansenii by a Dutch scientist named Pieter Bleeker. He was a zoologist and a military doctor who lived from 1819 to 1878. He found the first example of this fish in Manado, which is on an island called Sulawesi.
The fish was named in honor of Albert Jacques Frédéric Jansen, who passed away in 1861. He was an administrator in the Dutch East Indies and helped by providing the first fish specimen that Bleeker used to describe the species.
