Grazing sea urchins create ambient underwater noise on rocky reefs

London, July 23 : A new study has found out that chewing sounds from ravenous sea urchins cause ambient underwater noise on rocky reefs, which becomes a hundred times louder just before dawn and just after dusk.

According to a report in New Scientist, Craig Radford and his colleagues at the University of Auckland, New Zealand did the study.

The team recorded the sounds made by individual reef animals in the lab, and then compared them with the dominant sound in the natural reef din.

The urchins hide in crevices during the day, out of sight from predators, and emerge to feed at dusk.

"When they first come out I guess they're hungry, so they're eating with lots of gusto and making lots of munching noises," said co-author Andrew Jeffs.

Jeffs suggested that the peak in urchin feeding just before dawn may be their "supper", before they tuck themselves back into crevices for the day.

According to Jeffs, this regular noise could even help the larvae of fish and crabs find their way to reefs, as previous studies have found that some larvae can orient towards sound.

ANI