© Caroline V. Palmer
Injured corals develop colorful glowing "scabs" to help themselves heal, a new study has found.
When a coral is broken or wounded, it releases highly reactive atoms of oxygen known as free radicals to close up the gashes.
But these powerful molecules can also inadvertently kill off some of the coral's healthy cells. Hydrogen peroxide, for instance, is a common free radical in corals, and it can damage every part of the cell, from DNA to proteins.
Hurt corals have also been known to take on brightly colored glows, noted study leader and coral immunologist Caroline Palmer. Wounds on Acropora millepora
corals appear blue, for example, while injured tissues on Porites
species - like the raised and swollen patches seen above - are an "intense" bubble-gum pink.