This is the first in a series of marine ecology articles aimed at teens and produced as a set of the most often asked questions together with answers.
Q:
What is a whale song?
A: "Song" refers to the pattern of regular and
repeated sounds made by some species of whales, especially the Humpback Whale. Surprisingly,
these repeated sounds show a similarity to the repeated sounds used in human
song.
Q: Do whales make sounds the same way we do?
A: Not quite. They do use the air in their lungs but
don’t have vocal cords like ours. In dolphins, sound is made by the phonic lip
membranes in the top of the head (below the blow hole) which vibrate the
surrounding tissue. The rate of these vibrations and therefore the frequency of
the sound can be controlled with muscles.
Q: Can humans hear whale songs?
A: Humans hear sounds between about 20 and 20,000 Hz (the
larger the number the higher the pitch). The frequency of toothed whale sounds
ranges from 40 Hz to 325,000 Hz so we can hear their lower frequencies but not their
very high pitched ‘squeaks’. The frequency of baleen whale sounds ranges from
10 Hz to 31,000 Hz so many of their lower frequency songs are sped up
electronically so that we can hear them.
Q: Do all whales sing?
A: Most whales and dolphins produce sounds of varying
degrees of complexity but nothing like the elaborate songs of the Humpback
Whale. Another singing ‘star’ is the Beluga; sometimes called the "sea
canary", because it produces such a variety of whistles, clicks, and
pulses.
Q: Which whales are the best singers?
A: Two groups of whales, the Humpback Whale and the Blue
Whale from the Indian Ocean, are said to produce
the most complex series of repeated sounds at varying frequencies. The Humpback
Whale’s song has been described (biologist Philip Clapham) as "probably
the most complex in the animal kingdom".
Q: Why do whales sing?
A: Scientists believe that the songs (mostly seasonal) of
the Humpback whale (and some blue whales) are used in finding a mate. The
simpler sounds made by other whales have a year-round use. Toothed whales use
echolocation to ‘see’ the size and nature of underwater objects, to catch fish,
and probably to keep in touch with others in their pod.
Q: How long does a Humpback’s song last?
A: The whale can often repeat his ‘personal’ song, which
last up to 30 minutes or more, over and over again for several hours or even several
days. Whales that live in the same region (which can be as large as entire
ocean basins) usually sing similar sounding songs. Whales from different regions
sing quite different songs.
Q: How do scientists study whale songs?
A: The military developed underwater microphones to
listen for and track enemy submarines. Scientists can also use these
microphones (called hydrophones) to locate and track whale noises. Their
equipment allows them to calculate how far through the ocean a sound travels.
Q: How loud is a whale’s voice?
A: Humans can listen to loud sounds up to about 120dB
(decibels) before they feel pain and damage their ears. Some whales make sounds
up to about 200-220 dB which is about a billion times more powerful than your
loudest shout. These very loud low frequency sounds can travel for thousands of
kilometers through the water.
Q: Can humans mess up whale songs?
A: It looks like we can. Marine biologist Dr. C. Clark
says that the amount of noise from ships doubles every 10 years making it
harder and harder for whales to communicate, navigate, or find their food. Humans
need to use ships to transport goods across the ocean but it may be time we
tried to make them quieter for the sake of the whales.
Q: What is the longest distance a whale’s song can travel?
A: The Voyager Golden Records are recordings put in the two Voyager spacecraft
launched in 1977. The recording is meant for any intelligent extraterrestrial
life that might find the Voyager in the future. Without visiting us,
extraterrestrials will hear our Earth sounds, which include whale songs. In
about 40,000 years those songs will have traveled to a star in the Ophiuchus
constellation. That whale song might one day be heard 15,000 trillion
kilometers from where it was sung. Wouldn’t it be a tragedy if it is the only
whale song left in the universe when it gets there?
Thanks to photographers at Wiki for their wonderful work.
