Unicornfish

Unicorns graze among many of the world’s coral reefs. But instead of the graceful animals of mythology, they look more like cartoon characters. Their “horns” can be long, short, or even round and fat. And some have no horn at all.

These creatures are unicornfish. Biologists have identified about 20 species of them. They’re a type of surgeonfish—named for some scalpel-sharp spikes where the body and tail join. The adults of most species range from about one to two feet in length.

Unicornfish are found in tropical waters in much of the Indian and Pacific oceans—from the east coast of Africa to Hawaii. They generally live on coral reefs. Many of them eat algae—sometimes scraping it off the coral. Others eat tiny marine creatures. They feed during the day, then hide in cracks and cubbyholes in the coral at night.

Most unicornfish are bright and colorful, and many have prominent stripes or other patterns. What sets them apart, though, are the horns, which are found in about half of the unicornfish species. The horns come in a variety of shapes and sizes.

In some species, both males and females have horns. But in a few, it’s only the males. The guys may use the horns to attract mates. In some species, the males can change the color of both the horn and other parts of the body, making the horn stand out—perhaps a signal that he’s a strong mate. The males may also use the horns to chase off competition—protecting their own little patch of the reef.

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