T. Labhart et Ep. Meyer, Detectors for polarized skylight in insects: A survey of ommatidial specializations in the dorsal rim area of the compound eye, MICROSC RES, 47(6), 1999, pp. 368-379
Apart from the sun, the polarization pattern of the sky offers insects a re
ference for visual compass orientation. Using behavioral experiments, it ha
s been shown in a few insect species (field crickets, honey bees, desert an
ts, and house flies) that the detection of the oscillation plane of polariz
ed skylight is mediated exclusively by a group of specialized ommatidia sit
uated at the dorsal rim of the compound eye (dorsal rim area). The dorsal r
im ommatidia of these species share a number physiological properties that
make them especially suitable for polarization vision: each ommatidium cont
ains two sets of homochromatic, strongly polarization-sensitive photorecept
ors with orthogonally-arranged analyzer orientations. The physiological spe
cialization of the dorsal rim area goes along with characteristic changes i
n ommatidial structure, providing actual anatomical hallmarks of polarized
skylight detection, that are readily detectable in histological sections of
compound eyes. The presence of anatomically specialized dorsal rim ommatid
ia in many other insect species belonging to a wide range of different orde
rs indicates that polarized skylight detection is a common visual function
in insects. However, fine-structural disparities in the design of dorsal ri
m ommatidia of different insect groups indicate that polarization vision ar
ose polyphyletically in the insects. (C) 1999 Wiley-Liss, Inc.