CLUSTERING EXPERIMENT: BNU, 7 OCT 2013 -> CANCELLLED


Animal: fruit flies: Drosophila melanogaster (Meigen 1830)

CELL: 65 Droso in an ellipse with 2a=9.8cm, 2b=9cm, S=0.69 sq-dm,
density=93/sq-dm



Objective:
We wish to see if the Drosophila form one or several clusters.

Summary: 
For the transfer from their storage tube to the experiment cell the Drosophila
have been put to sleep with carbon dioxide. It took about 10mn for them to
wake up. In the course of the experiment a square of cardbord was added because
without it the auto-focus of the camera did not work very well.
The height of the cell is 5mm which does not allow the Drosophila to fly. 
However, they can walk faster than ants of same size. Their speed can be
estimated at around 2cm/s; in some cases it can reach 3-4cm/s.
We are grateful to Prof. Fei Dou (douf@bnu.edu.cn) whose group
provided the drosophila.
Pictures were taken at a rate of one per minute. The experiment was
stopped after one hour
because nothing new was happening.
At the end of the experiment it was realized that the source of light
under the box raised its temperature. Therefore this experiment
was cancelled and repeated in better conditions (cold source
of light and higher density of drosophila).

Chronology:

f1  -> 22:36 -> Start

f2  -> 22:57 -> The Drosophila have moved toward the edge of the
container. 
About 62% of them stay either on the vertical edge or in
a ring of a width of 10mm next to edge.

f3 -> 23:04 -> There is a loose and temporary gathering of flies which
last less than 1mn.

f4 -> 23:05 -> This photo shows that the gathering has been scattered
within one minute.

f5 -> 23:08 -> This photo and the next (f6) taken one minute later
show another temporary gathering.

f6 -> 23:09