Subject: echolocation

Tokitae (tokitae@bellsouth.net)
Sun, 25 Apr 1999 22:50:33 -0400 (EDT)

>I'm currently teaching a unit on whales to second graders.   I am using
>several different sources and am finding conflicting information on
>which whales use echolocation and the purpose.   Specifically...one
>source states that only toothed whales use it for locating food while
>another source says all whales use it to find food and to prevent
>collisions with large objects.   Would you have any further information
>on this?  I'm concerned that any information I introduce should be
>accurate.  And finally...if only toothed whales do use echolocation, how
>do baleen whales locate food and avoid danger if their vision is also
>poor.  I would think they would need to rely on their other senses.
>Many thanks!

        There are no recordings of sounds from baleen whales that indicate
that they use echolocation, so the question of how they find food is a good
one. Although baleen whales seem to have good vision, it's not much good in
seawater past 30 to 50 feet. The answer lies primarily in their excellent
hearing. Krill and baitfish, the food of baleen whales, emit noise when in
large, dense congregations, and with birds and other fish and mammals and
other whales closing in on the prey there could be enough volume to attract
baleen whales. I'm not familiar with any studies that demonstrate this, but
by process of elimination that seems to be the case. Other senses, like
taste or smell could possibly lead them to concentrations of prey, as could
a tactile sense of the currents and upwellings which would give rise to
productive waters and hence, lots of food. When they get close, vision would
take over. Avoiding danger is a different question, and since the only
predators would be sharks (on newborns) and orcas, there's no use trying to
flee because the predators are generally faster, so avoiding danger is a
matter of defensive postures, not flight. A distant warning system like
echolocation could be useful anyway, I'm sure, but they don't seem to have one.


Howard Garrett
Tokitae Foundation
Lolita Campaign Coordinator
(305) 672-4039
tokitae@bellsouth.net

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