Wednesday, 17 December 2014

Humpback Whales Sing Tick-Tock Songs For Supper

Humpback whales (Megaptera novaeangliae) are known to employ group foraging techniques, however details on how individuals coordinate with each other still remain a mystery.

A new study by Susan Parks, assistant professor of biology in the College of Arts and Sciences, in collaboration with a consortium of other researchers examined the importance of specific auditory cues that these whales emit as they search the deep ocean for prey.

"Humpback whales are known to cooperate with others to corral prey near the surface. Recent studies suggest they may cooperate [with each other], when feeding on bottom prey, as well." said Parks, who studies marine science and acoustic communication.

Parks was part of a collaborative multi-institutional consortium that has spent a decade monitoring humpback feeding behaviors in the Gerry E. Studds Stellwagen Bank National Marine Sanctuary, off the coast of Massachusetts.

Humpback whale breaching
Humpback Whale
Whales were tagged with special underwater recording devices so Parks could determine how specific acoustic sounds correlated with successful seafloor feeding.

The researchers discovered that whales make "tick-tock" sounds when hunting together at night in deep, pitch-black water, but stay silent when hunting alone.

What was on menu? Mainly sand lance (Family: Ammodytidae), eel-like fish known to bury themselves in the sand of the ocean floor. Parks suggests that whales' vocal sounds may help flush the sand lance out of hiding to where they're scooped up and eaten.

Pacific sand lance (Ammodytes hexapterus) burrowing into the sand, only head visible
Pacific sand lance (Ammodytes hexapterus) burrowing into the sand
The clock-like sounds created by whales may also serve as a dinner bell of sorts for other nearby whales during late-night feedings.
"Hints of behavior suggest that other whales who overhear the sounds are attracted to them and may eavesdrop on other whales hunting for food." Parks added.

Susan parks, biology professor
Susan Park

Parks SE, Cusano DA, Stimpert AK, Weinrich MT, Friedlaender AS, & Wiley DN (2014). Evidence for acoustic communication among bottom foraging humpback whales. Scientific reports, 4 PMID: 25512188

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