Baleen whales are among the largest creatures in the ocean, but that doesn’t mean they’re safe from other animals. A pod of orcas can take a giant baleen whale down, and these filter-feeders are particularly vulnerable when they have calves.
New research from University of Washington marine scientist Trevor Branch has revealed a defense mechanism some baleen whales appear to use to protect themselves against attack. They’ve evolved to become baritones — essentially the Paul Robesons of the whale world — they sing really, really low.
Baleen whales communicate with each other across the expanse of the ocean by singing. Some songs — like those of gray whales and humpbacks — are elaborate and higher-pitched. These songs are within the hearing range of orcas and can potentially be used to track down their prey.
Other songs, like those of blue and fin whales, are low-pitched (often below 100hz), loud and monotonous. The loud, low songs can travel long distances through the water, but orcas can’t hear them, giving the larger whales the ability to communicate while avoiding detection.
The difference between the two types of song does not appear to be random. The UW analysis found that the altos of the whale world — many of which can be found in shallow waters off Oregon and Washington — fall into a group of baleen whales known to fight back against orca attacks. Their bodies are stubbier, more maneuverable, and they’re more likely to congregate in higher numbers in shallow water.
File photo of a blue whale off the coast of Bandon, Oregon. An analysis from the University of Washington finds that blue and some other large baleen whales sing very low pitch songs to avoid detection by orca predators.
Credit Courtesy of Leigh Torres, photo taken under under NOAA/NMFS permit #21678
The baleen whale baritones, on-the-other-hand, are often solitary creatures that stay in deep water, only coming together to mate. These whales flee when orcas attack. Their long, powerful streamline bodies allow them to sustain high speeds for long periods of time. They simply outrun the hunters.
“The largest flight species (blue and fin whales) are all-but acoustically invisible to killer whales,” the study concluded.
The findings suggest the evolution and behavior of at least some baleen whales has been significantly shaped by fear of orca attack.
The research is published in the journal Marine Mammal Science.
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