It quacks like a duck, sort of. But the mystery creature of the Antarctic is more likely a whale.
Submariners in the 1960s recorded strings of quick heartbeatlike pulses and nicknamed the unknown source a “bio-duck.” Whatever it is sounds off mostly in winter and spring in the Weddell Sea off Antarctica and the waters off Western Australia.
The sound is “way too loud for a fish,” says marine biologist Denise Risch of Integrated Statistics in Falmouth, Mass. Listeners have proposed sources from military hardware to marine mammals such as minke whales.
Very little is known about these whales’ vocalizations; researchers have identified only a few of the various minke species’ sounds, including a “boing” and what’s called a “Star Wars” vocalization. In 2013, researchers for the first time placed acoustic tags on the Antarctic minke (Balaenoptera bonaerensis). Tags from two whales recorded some sounds already linked to the species.
But over the course of 18 hours, one of the tags picked up bio-duck beats before and during a whale’s feeding dive. Because researchers following the whales saw no other marine mammals nearby, Risch and colleagues conclude April 23 in Biology Letters that minke whales are the bio-ducks.
Not your wooo-wooo whales
Minke whales can make sounds that don’t even sound like an animal and defy the popular notion of the drawn-out, wavering “whale song.” Audio clips courtesy of D. Risch
The Antarctic minke species makes a heartbeatlike “bio-duck” sound (audio in clip is amplified).
The common minke species makes a “boing” sound (clip recorded in the North Pacific).
The dwarf minke species has a “Star Wars” vocalization (clip recorded at the Great Barrier Reef).