hide
Free keywords:
-
Abstract:
The 3 Ocelli of the blowfly Calliphora erythrocephala,
grouped close together on the top of the head (Fig.1), have
large, extensively overlapping visual fields. Together they
view the entire upper hemisphere of the surroundings plus
part of the lower hemisphere (Fig. 5, 7). It is shown for
the lateral ocelli that despite the underfocussing of the
ocellar lens large patterns are imaged on the receptor
mosaic. Because of the astigmatism of the lens, patterns in
longitudinal orientations are more accurately represented
than in others (Fig. 3). Nevertheless, an artifical horizon
rotated around the long axis of the animal does not elicit
head roll. Likewise, changes of overall brightness in the
visual field of the median and one lateral ocellus elicit
only weak phasic-tonic "dorsal light responses" of
the animal which supplement the tonic dorsal light responses
mediated by the compound eyes (Figs. 9, 10). Our results
show that, in Calliphora, the ocelli have little
influence on head orientation during flight, and must be
assumed to serve other functions.
