At Oregon State University and the University of Hawaii scientists discovered that Dolphins use choreographed night-time "dance" to finish their predation and then throw into the circle of fish in pairs, then feed 15 seconds and letting the next pairs in line take their turn.

This study highly expands proficiency of spinner dolphin behaviour and it shows technological advancements in acoustical monitoring of underwater ecosystems.

First, a group of around 20 dolphins swim side by side in a straight line until finding lanternfish. When they came to within five meters of the prey , they pull into a tight circular formation and iteratively swim up and down vertically, in that way doing "the wave".

When lanternfish became concentrated , the dolphins shrank their circle, forming 10 pairs. The one o`clock pairs and seven o`clock would feed for 15 seconds and hand over and they let other pair to do the same.

They would be feeding 5 minutes each and every dolphin got chance to be feeded. None of the dolphins break the circle and they were very synchronized.

Researcherers are wondering how the dolphins communicate. Dolphins are often vocal and use frequency modulated whistles. But while hunting prey, they did not make whistles but series of clicks.

"Whistles are omni-directional, like turning on a light bulb in a room," Benoit-Bird said. "Clicks, on the other hand, are directional like a laser. We think it may be a strategy to communicate only within the group and not to other potential lanternfish predators. Tuna and billfish are looking for the same prey and they can hear the whistles but not the clicks because the frequencies are too high and so focused.

Spinner dolphins are in tropical and subtropical waters, near island chains and offshore.

Kelly Benoit-Bird, a marine ecologist at Oregon State University was lead author on the study.

Kristina Zolota