Scientists have found the source of a mysterious outbreak that killed sea urchins across the Caribbean last year. Researchers reported Wednesday that a tiny parasite is to blame for the die-off. The long-spined sea urchin hides out in reefs and eats the algae that grows on corals. But in 2022, many of these urchins started shedding their spines and dying. After testing the sea urchins for genetic clues, scientists found that single-celled creatures known as ciliates were making them sick. These same creatures may also be the cause of an outbreak in the 1980s that killed almost all the urchins in the region, though scientists can't say for sure.
