Voice box In the laboratory, the scientists blew air through the voice boxes under controlled conditions to see what tissues might vibrate. They also created computer models of the sei whales vocalizations and matched them to recordings of similar whales taken in the wild. Whales ancestors were land animals that moved into the oceans about 50 million years ago. Elemans said the animals voice box changed over tens of millions of years in order to make sounds underwater. Baleen whales do not have teeth or vocal cords like humans and other mammals. Instead, they have U-shaped tissue in their voice boxes that permits them to breathe a lot of air very quickly. Their voice boxes also contain a large cushion of fat and muscle not seen in other animals. Whales sing by pushing the tissue against the fat and muscle cushion.

Elemans said baleen whales depend on the production of sound to communicate in the dark of the deep oceans. For example, humpback females and their calves communicate with each other by voice, and humpback males sing to attract females, he added. Jeremy Goldbogen is a professor of oceans at Stanford University, who was not involved in the research. He said, This is the most comprehensive and significant study to date on how baleen whales vocalize, a long-standing mystery in the field. The whale voice boxes tested were from younger animals, not adult males, who do the singing. Because of that, whale expert Joy Reidenberg said further experiments on adult males are needed to confirm the studys findings. Reidenberg works for the Center for Anatomy and Functional Morphology at the Icahn School of Medicine at Mount Sinai in New York City. She noted that the research is probably as close as we can get to reproducing how whales sing.

Right now, our technology involves sticking a scope into a whale to see what exactly is vibrating, she said. Since youre never going to be able to do that in a wild animal, these experiments are the next best thing. Shipping noise As loud as whales songs are, the study suggests that whales cannot produce sounds louder than noise from the shipping industry, Elemans said. Theyre really affected by (shipping noise) and it significantly reduces their ability to communicate, he said. Theres just no way for them to get louder. Because some whales sing as a mating call, the shipping industrys interference with those songs is a concern, said Michael Noad. He is director of the Center for Marine Science at the University of Queensland in Australia. He also was not part of the Nature study.

For whale populations that are really dispersed, like the Antarctic blue whales, they might not be able to find mates in a noisy ocean environment, he said. However, whales like humpbacks that gather in big numbers are more likely to ignore such noise pollution.