Hello Minn~
You?re right; this subject *is* fascinating and amazing. :) It?s also
very complex.
According to New York Times writer Henry Fountain, ?Honeybees can go
home again, and again, and again. Their ability to return directly to
the hive after a rambling flight in pursuit of food is remarkable,
although ***exactly how they accomplish this has been unclear***.?
(?Supernavigator?s Secret,? by Henry Fountain, New York Times, Oct.
28, 2003; as seen in this pdf file:
http://www.me.berkeley.edu/ME230/me230Exam03.pdf ; emphasis mine.)
This may explain why you?re feeling a little confused by the
descriptions of how bees navigate: Scientists aren?t exactly clear on
it, themselves!
Most scientists seem to believe that bees use ?vector navigation.?
This means they are forever calculating the distance they?ve traveled
while they?re foraging for food; therefore, when it?s time to return
to the hive, they already know how far they need to travel back home.
According to the Times article, scientists in Germany and the U.K.
have used radar to test this theory. Believe it or not, the scientists
placed miniature transponders on honeybees, so they could track them.
?In a large mown field outside a German village, they allowed the bees
to reach a feeding station. But before the bees left to return to the
hive, the researchers moved them to another location in the field,?
writes Fountain.
The results revealed that the displaced bees flew in the direction
that *should* have taken them back to the hive, *if* they?d still been
at the feeding station. Some poor bees even flew the entire route
before they found themselves lost and had to hunt around for their
hive. Scientists know that the bee?s sense of distance-traveled is so
keen, they can even compensated for ?wind drift.?
Proving some theories wrong, the bees in this test *ignored* landmarks
(which had been placed in the return path in order to test the
landmark theory).
However, the Times article admits that past studies seem to show that
bees do ?take in? (through their retinas) the images they fly past ,
and use this as part of their navigation. It also suggests that bees
orient themselves according to the sun?s position in the sky?-which
brings us to your question about ?polarization.? Bees may have
?internal compasses? that help them translate ?the polarization of
sunlight and ultraviolet sensors to track the horizon, which helps
them measure movement.?
According to Dictionary.com, ?polarization? means: ?A process or state
in which rays of light exhibit different properties in different
directions?? (http://dictionary.reference.com/search?q=polarization )
Merriam-Webster clarifies: ?The action or process of affecting
radiation and especially light so that the vibrations of the wave
assume a definite form.? (http://www.m-w.com/cgi-bin/dictionary )
According to one educational website, ?If the sun is not visible but a
blue sky is there, the sky light is polarized and the bee's eyes can
detect this polarization and their brains can ?calculate? the position
of the sun. If you put a sheet of ?Polaroid? over the hive and twist
it 90 degrees, the bees will fly 90 degrees in the wrong direction for
the food, since the plane of polarization of the light has shifted 90
degrees. Our eyes have the ability to see the plane of polarized light
in the sky. A small hour glass shaped patch at the side of our retinas
is polarized and can see the plane of polarization of light. This
patch is called ?Haidinger's fringes? and as it is at the side of the
eye, you have to learn to see out of the corner of your eye to see the
plane of polarization. Normally we use the centre of the retina, the
macula, which does not have this property.? (?The Senses of Bees,?
Professor?s Kerkut?s Home Page, http://www.soton.ac.uk/~gk/index.htm )
Bees have five eyes, including two ?compound eyes? that have 7,000
hexagonal facets. The other three eyes discern light intensity,
scientists believe. (?The Buzz on Bees,? by Jen Waters, The Washington
Times, http://www.washtimes.com/metro/20030604-104141-3304r.htm )
Apparently, ?bees are designed to maneuver so the image speed remains
constant, preventing them from running into things,? says Jen Waters
of The Washington Times. In other words, bees seem to alter their
flight speed so that images they see move at a constant rate.
(?Bee Where?? by Sara Cross, Nature, Feb. 3, 2000;
http://www.nature.com/nsu/000203/000203-10.html )
This theory is called ?optic flow.? And may be somewhat similar to how
humans judge how fast a car is moving: by noticing how fast the trees
are flying past, as wel look out the car window. (?Behavioral
Communications,? Bee Biology,
http://www.cyberbee.net/biology/ch6/dance3.html ) Bees, though, appear
to be able to remember how much optic flow occurred, and use that
information to judge their return flight.
Amazing, indeed!
Kriswrite
Keywords Used:
"how bees navigate"
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bees polarization
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bees image speed
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