When Attacked, Corals Send Out Chemical Signals to Recruit Bodyguard Fish – Smithsonian Magazine Online Article
Corals are constantly under attack. Sea stars and other predators would love to take a bite, coral diseases lie waiting to take them out and many human-caused stresses persist in the water they inhabit, such as pollution, warming temperatures and rising acidity.
One of the first signs of a sick reef is the takeover of seaweeds, which continually threaten even healthy corals. However, corals aren’t alone in the fight against greenery, according to new research published in Science. When attacked, some corals send out chemical signals to their bodyguards—small goby fish—who scrape off or eat the coral-choking seaweeds.
Turtle weed (Chlorodesmis fastigiata) threatens corals because, upon contact, it releases a noxious chemical that disrupts their food source, the photosynthetic algae (zooxanthellae) that live inside their cells, ultimately leading to coral bleaching. Although most fish don’t have a palate for such toxic seaweed, authors Mark Hay and Danielle Dixson from the Georgia Institute of Technology observed coral gobies—small fish that spend their lives living in a single coral colony—eating it, and they wondered if there was more to this behavior than taste.
Photo: Courtesy of Danielle Dixson