In Message Mon, 3 May 1993 15:02:17 GMT,
"Dr. M. Giurfa" <[log in to unmask]> writes:
>Berlin, 3.5.93
>..
>..
>UV-Orientation:
>..
> There is certainly a spectral pattern in the sky which depends on the
>angular distance to the sun. As the radiant intensity of scattered light
>is inversely proportional to the fourth power of wavelenght, the relative in-
>tensity of short wavelenght radiation is higher in scattered skylight than
>in direct sunlight. The opposite is valid for longer wavelenghts (this
>sounds terrific!).
>..
> To put it simply, if one imagines the sky over an observer, it should
>be represented like a dome. In this dome, longer wavelenghts will be around
>the solar spot whereas shorter wavelenghts will be mainly in the antisolar
>meridian of the sky (the half part of the dome opposed to the sun).
>..
> But what does mean "shorter" and "longer" wavelenghts for the bees'
>eye? After the comments on this topic that we got, we know that bees can see
>colours, from UV (the shortest wavelenght they can see) until green (the
>longer wavelenght they can see). In other words, with a little bit from
>imagination, the sky dome should appear to the bees like an UV dome with a
>green sun. To prove that this is not only a Sci-Fi exercise, people like
>Samuel Rossel (Freiburg, Germany) and Ruediger Wehner (Zurich, Switzerland)
>raised the question of the use of spectral patterns in the orientation stra-
>tegies of honeybees.
>..
> They asked, for example, whether UV as a colour is used in a particu-
>lar orientation strategy. They trained bees to a known food source and then
>they recorded the dances of the foragers once in the hive. Bees danced
>on an horizontal surface and were covered by a plexiglass dome (they could not
>see neither the sky nor the sun through it). A hole was opened in the dome and
>a spot of UV light was offered there. Dances were recorded and deviations of
>the correct direction to the food source measured. It was promptly demons-
>trated that bees can actually use UV as an orientation cue but in a BROAD
>WAY and not in a fine way (as wrongly suggested by a previous mail): BEES
>INTERPRETED AN UV SPOT AS LYING ANYWHERE WITHIN THE ANTISOLAR HALF OF
>THE SKY. That means that, when bees see an UV patch, "they know" that they
>are looking in the antisolar half of the sky. With the same kind of
>experiments, it was demonstrated that ANY GREEN SPOT is taken for the sun
>and dances are reoriented accordingly.
>..
> To summarize it, spectral information can be used in a broad orien-
>tation strategy. A green spot represents the sun whereas an UV spot repre-
>sents a patch lying anywhere within the half of the sky opposed to the sun.
>..
> If somebody wants to read more about this, I would recommend "The
>bee's celestial compass" from Ruediger Wehner, in "Experimental behavioural
>Ecology and Sociobiology"(Hoelldobler & Lindauer eds), G Fischer, 1985.
>..
> Finally, a personal request. I think that contributions to the net
>based on popular beliefs or some kind of mystical knowledge do not help but
>simply add to a great confusion. So, I would like to have comments based on
>scientific literature and on replicated experiments. I hope that this does
>not sound aggressive. I only believe that this is the way in which all the
>people can really benefit from the net.
>..
> Cheers,
>..
>..
> Martin Giurfa
>..
> Institute fur Neurobiologie
> Freie Universitaet Berlin
> Koenigin-Luise-Str. 28/30
> 1000 BERLIN 33 - GERMANY
>..
> [log in to unmask]
>..
>..Very good suggestion !
Harald Esch
Department of Biological Sciences
University of Notre Dame
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Harald E. Esch ("[log in to unmask]")
Professor, Dept. Biological Sciences
University of Notre Dame, Notre Dame IN 46556
Phone: (219) 631-7025 FAX: (219) 631-7413 Dept. Office: (219) 631-7186
=-=-=-==-=-==-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
|
