Dive into the coral reefs of Southeast Asia or Australia and you’ll likely spot a wrasse. But which of the hundreds of kinds of wrasses will you see?

These fish can be an inch to more than eight feet in length. They can be skinny like cigars or hefty like footballs. Some are somber-colored; others look like they’re attending a rave. Different species have their own creative feeding strategies: humphead wrasses crush shellfish; tubelip wrasses slurp corals and cleaner wrasses act like carwashes, eating parasites and dead tissue off other sea creatures.

This spectacular diversity stems from wrasse ancestors that migrated from the prehistoric Tethys Sea to the area that now bridges the Pacific and Indian Oceans. There, in a vast and vibrant cradle of coral reefs, they settled and steadily diversified over tens of millions of years.

Their story fits into a larger pattern. This region, the Central Indo-Pacific, has become the hot spot with the most biodiversity in Earth’s oceans because many ancestors of today’s marine life colonized it so long ago, according to a recent paper in Proceedings of the Royal Society B.