Divers have shared intriguing footage of a fish tapping the sand off the coast of Mustique Island in the Caribbean Sea.
“Tap, tap, tap – have you ever seen a fish tapping the sand?” asks The Marine Diaries on Instagram while sharing puzzling footage taken by marine biologist Laura Chapel.
In the video, a flying gurnard (Dactylopterus volitans) swims just above the seabed, tapping the sand with its fins. Chapel captured the footage during a dive off the St Vincent and the Grenadines island, which lies a hundred miles west of Barbados.
The behaviour might seem strange but drumming on the seabed has an important purpose – disturbing potential food items that might be hiding in the sand.
“As they scratch and probe the seabed, they uncover benthic [bottom-dwelling] prey like crustaceans and small fish which make tasty snacks,” says The Marine Diaries. “Sometimes they’re even followed by other fish that take advantage of this curious behaviour for an easy meal!”
Flying gurnards can’t fly in the traditional sense. These bottom-dwellers “get their name from their wing-like pectoral fins which are used as a shield deterrent,” says Chapel. If they see a threat in the water, they can expand their ‘wings’ to make themselves look bigger and more intimidating in the hope of scaring off their potential attacker.
The “gurnard” part of their name originates from the Latin and Old French for “to grunt” because of the strange grunting sounds these fish can make. “Unlike humans, who make sounds using their vocal cords,” explains scuba diving brand Mares on its website, “flying gurnards use their swim bladder and jaw muscles to produce these grunt-like sounds to communicate with each other or scare predators.”
Image and video credit: Laura Chapel | @laura_the_marine_explorer
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