CLUSTERING EXPERIMENT: BNU, 5 Nov 2013


Animal: ants (Terramorium, Caespitum, Linnaeus 1758)

CELL no 1 (20cm x 20cm),  130 ants -> density= 32/dm2
CELL no 2 (20cm x 20cm),  210 ants -> density= 52/dm2
CELL no 3 (15cm x 15cm),  128 ants -> density= 57/dm2
CELL no 4 (15cm x 25cm),  190 ants -> density= 84/dm2
CELL no 5 (09cm x 09cm),  012 ants -> density= 15/dm2
CELL no 6 (09cm x 09cm),  038 ants -> density= 47/dm2
CELL no 7 (09cm x 09cm),  030 ants -> density= 37/dm2
CELL no 8 (09cm x 09cm),  024 ants -> density= 30/dm2

The numbers of ants in each cell were counted on the screen 
after zooming in.

The strips of paper between the cells are impregnated with citronella oil
which is a well-known repellant for ants (as well as mosquitos). 
However, in the
course of time over a time interval of several hours some ants will
nevertheless cross to
other cells. 
The advantage of these strips over a more rigid container is that the ants 
will mostly stay away from
them whereas they will tend to move to the edge of a container where they will 
then remain. 

One of the purpose of this experiment was to investigate
the effect of the size of the area over which the ants are
spread in order to see effects due to the range of the interaction. 

Summary: 
After the ants were transferred from their container to the cells, they 
were moving much faster (in a kind of panic mode) so that
many crossed the boundaries of their cell, especially in the
smallest cells.
However, this 
state of excitation lasted only between 5 and 10mn. After that the 
ants mostly remained in their cell.

One interesting (and unexpected) observation consisted in
the fact that a cluster of ants can move (globally) from 
one place to another. First, the initial cluster seems to
fall apart but it is reconstituted within a few minutes at a
nearby place. This can be observed in images (f6-f10) 
for cell 3 and 4, in (f12-f14) for cell 2, in (f17-f18) for
cell 4.
A similar effect has been described for bees in the papers by
Lecomte (see above) and was also observed in our own
bee experiments (see above).

A picture was taken every minute. The 19 photos attached
were selected from a total number of 184.

Chronology:
f1 (16:38): First picture
f4 (17:00): 4 clusters 
f7-f10 (17:17-17:23) Decomposition and reconstitution of clusters
f19 (19:42): Last picture