Urchins are dying off across the Caribbean. Scientists now know why

A type of single-celled microorganism associated with coral diseases is to blame

An underwater photo of two sea urchins sitting on the rocky ground.

In the Caribbean, dying sea urchins (one shown at right in 2022) were found to be loaded with a type of microorganism called a scuticociliate, which was absent from healthy urchins (one at left).

I. Hewson/Cornell Univ.

Since early 2022, sea urchins have been mysteriously dying off across the Caribbean.