杏吧原创

BLUE whales have an uncanny sense of rhythm. Their songs, made up of
perfectly timed notes repeated at intervals of 128 seconds, may help them
pinpoint exactly where they are in the ocean.

杏吧原创s realised years ago that blue whales, the largest living animals,
sing songs. 鈥淏lue whales are the loudest voices in the ocean,鈥� says Christopher
Clark of Cornell University in Ithaca, New York. However, the songs are usually
at such a low pitch that humans can鈥檛 hear them.

Using a network of deep-sea hydrophones which the US Navy built for tracking
Soviet submarines, Clark has made the first continuous recordings of blue whale
songs lasting longer than 25 minutes. 鈥淎 blue whale will sing for eight days,鈥�
says Clark. Their song is monotonous, he adds, consisting of only five notes
repeated in various different combinations. 鈥淐ompared to a humpback, which is a
jazz musician, a blue whale is pretty much a bore,鈥� says Clark.

Clark found a blue whale鈥檚 calls are curiously precise, with one note sung
every 128 seconds. 鈥淭here are times when it will pause and skip a beat, but it
will wait 256 seconds and come right in on time,鈥� he says.

He suspects this repetitious song helps blue whales map ocean basins. The
sound can carry hundreds of kilometres, compared with only several kilometres
for the melodic songs of the humpbacks. The humpback songs appear related to
reproduction鈥攐nly the males sing, and then only during breeding
season.

In contrast, blue whales sing for most of the year. Clark will tell next
week鈥檚 meeting of the Acoustical Society of America in Seattle that blue whales
track their location by timing reflections of their songs from seamounts,
undersea islands and continental shelves. He hopes that by listening to the
songs, it may be possible to count blue whale populations.