Coral for the foundation of complex and diverse marine ecosystems. Here, a pink Christmas tree worm rests on the side of a boulder star coral. Image credit: laszlo-photo/Flickr
When tiny coral larvae hatch, they have only a short time to find the host that will become their lifelong home. How these nearly-microscopic organisms accomplish such a feat—when an entire ocean of peril and danger stands in their way—has been a mystery.
Now, new research suggests that the larvae use the sound of the reef as a beacon and "dance" their way towards their new homes.The larvae look like tiny eggs, covered in yet smaller hairs, and belong to the Cnidaria phylum, which also includes anemones.
By using a "choice chamber"—which offers invertebrates two contrasting environments and allows them to choose between them—a research team led by Steve Simpson at the University of Bristol found that the larvae preferred an environment in which recorded reef sounds were played over a silent one.
It's all song and dance under the sea, but Image anthropogenic noise may drown out the music. credit: imagesdisney.com
While the researchers were unable to determine the exact reason for this, Simpson suggested that:
At close range sound stirs up water molecules, and this could waggle tiny hair cells on the surface of the larvae, providing vital directional information for baby corals.
If sound does play a significant role in this fragile stage of the coral life cycle, anthropogenic noise—from boats, drilling, and other human activities—may be one more threat to the survival of reef ecosystems around the world.