Subject: How do whales navigate?

Caroline DeLong (delong@hawaii.edu)
Fri, 23 Apr 1999 11:50:52 -1000

At 02:02 AM 4/20/99 -1000, you wrote:
>Hello!
>
>My name is Stefan Bojnert. I=B4m a student at an Swedish university.
>
>I=B4m doing an home-essential for my Biologi.
>
>I have always been intrested i whales, and there way to navigate. So=20
>i thought that it would be perfect "job" for me.
>
>But when i=B4m trying to find information about this topic, i notise=20
>that it=B4s very hard to find any.=20
>All books says the same thing. "Whales navigate with sounds".
>It=B4s has to be more than that. Hasn=B4t it?
>Cant whales "feel" their way to diffirent locations by using "the=20
>earth magnetic fields"? Or navigate by the stars?
>
>Do you know where I can find any information on this? Here in Sweden=20
>it seems that this topic (whales navigation) haven=B4t been discoverd=20
>yet.
>
>And when im at it, I can also ask if you knows anything about the=20
>ways ordinary fishes finds their way in the ocean? Are they only=20
>using their "smelling-senses"?
>
>All help would be appriciated.
>
>Regards
>
>Stefan Bojnert
>
>Ps. I was in Hawaii last year, and I loved it.

Dear Stefan,

The sense of sound is often considered the major sense used by cetaceans
(whales and dolphins).  Sound propagates much more effectively in water
than in air.  This, along with the fact the water can be murky or dark
(producing low visibility conditions), makes sound a great way for
cetaceans to gain knowledge about their environment (e.g., navigate, find
food, avoid predators).  Sound is thought to be used for both echolocation
and communication in odontocetes (toothed whales).  Mysticetes (or baleen
whales) are not known to echolocate (although at least one scientist
believes that humpback whale 'songs' could be echolocation signals).

Odontocetes probably do a lot of their navigation using echolocation.
Echolocation works like this- the whale or dolphin sends a series of short
broadband pulses (or 'clicks') through their melon (head region), which
bounces off objects and returns an echo to the animal.  It is generally
thought that they receive these echoes in the lower jar region, where they
are transmitted via fatty channels to the ear.  The echoes can tell them
the position, size, shape, and material composition of objects (Au, 1993;
Nachtigall, 1980).  We know from early work on echolocation that dolphins
can locate and discriminate among objects when they are 'blindfolded' (they
are wearing soft plastic eyecups).

Here are some reference for you:

Au, W.W.L.  (1993).  The Sonar of Dolphins.  New York: Springer.
This is THE book on dolphin echolocation. Here you will find lots of
studies and references.

Nachtigall, P.E.  (1980).  Odontocete echolocation performance on object
size, shape, and material. In R. G. Busnel & J. R. Fish (Eds.), Animal
sonar systems  (pp. 71-95). 	New York: Plenum Press.

Evans, G.H.  (1987).  The Natural History of Whales and Dolphins.  New
York: Facts on File Publications.
This is a good general reference.


The biomagnetic sense also may be used by cetaceans (whales and dolphins)
to navigate. We know that other animals could use that sense to navigate.
For example, homing pigeons can orientate in the absence of any cues (sun,
stars, etc) but are disoriented in the presence of strong magnets.
Anatomical studies of a variety of animals have revealed particles of
magnetite, usually in the head or neck region (however, it is hard to tell
whether the magnetite particles came from the animal or the dissecting
instrument). Magnetic material, and possibly magnetite, has been found in
the brains of a bottlenose dolphin, Cuvier's beaked whale, Dall's purpoise,
and the humpback whale (Bauer et al., 1986). In the UK, Margaret Klinowska
(1986) has found a correlation between the sites of live cetacean
strandings and the presence of local magnetic field lines intersecting the
coast.  No such correlation can be found for strandings of animals already
dead nor for sites where magnetic field lines ran parallel to the coast.
More research is needed in this area to know if cetaceans are really using
a biomagnetic sense to navigate. =20

Here are some references for you:

Bauer, G.B., Fuller, M., Perry, A., Dunn, J.R., and Zoeger, J. (1986).
Magnetoreception and biomineralization of magnetite in cetaceans.  In J.L.
Kirshvink, D.S. Jones, & B.J. McFadden (Eds.), _Magnetite Biomineralization
and Magnetoreception in Living Organisms (pp. 489-508).  New York: Plenum
Press.

Klinowska, M. (1986). The cetacean magnetic sense-evidence from strandings.
 In M.M. Bryden & R.J. Harrison (Eds.), _Research on Dolphins_
(pp.401-432).  Oxford: Clarendon Press.      =20

I recommend searching a database like Biological Abstracts in your library
for more recent information, using keywords like "whale" and "biomagnetism"
and/or "magnetite." If your libraries in Sweden don't carry the books I
mentioned, you can order them online at sites like amazon.com.

Good luck with your studies!
Caroline
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Caroline DeLong
Marine Mammal Research Program=20
Hawaii Institute of Marine Biology
P.O. Box 1106
Kailua, HI  96734
delong@hawaii.edu