The male front narrower than the first falgellomere, and eyes very close to each other with ommatidia
uniform in size (fig.
The input from the thousands of ommatidia
is combined by the brain, to form a high-resolution image.
Here, the spaces between these artificial ommatidia
can stretch to allow transformation in geometry from planar to hemispherical.
Lesions in the ommatidia
of the eye were present in animals from both Rhode Island and Maine (Fig.
They consist of hundreds of thousands of tiny lens-capped optical units called ommatidia
This section has some nice photographs and subjects, particularly a good description of the visual acuity that lobsters possess using ommatidia
Eyes (in frontal view) conspicuous, oval-shaped; in lateral view eyes covering one third of head; 12 ommatidia
across at widest portion of the eye (worker [N = 3] with only nine ommatidia
at widest portion of the eye).
in preparation) and further suggest a tendency towards parallel evolution in some traits in these ants, including clypeal reduction between antenal lobes, reduction of the eyes to entirely absent or with few ommatidia
, reduction in the number of antennal and palpal segments, and perhaps, simplification in sculpture.
Eye convex, protruding from side of head, centered on midpoint of side of head, without hairs between ommatidia
Eyes bare, broadly abutting medially for length of 5 ommatidia
An open rhabdom structure in the ommatidia
of Heteroptera is considered a synapomorphy for Heteroptera, in contrast to the fused rhabdoms in Auchenorrhyncha and Coleorrhyncha (Fischer et al.
vary in size and resolution and are fused together, forming different points of focus.
318), it has been obvious for many years that such structures need not be exceptionally small and need not be extremely like ommatidia
to behave like ommatidia
For only one example, the necessity for some fiddler crabs to detect prey approaching over the horizon has caused the evolution of specific arrangements of the ommatidia
in the eyes, which in turn favor males which erect vertical structures at the burrow (Christy and Salmon 1991).
However, it is more likely that arachnid eyes evolved from the expansion of individual ommatidia
for the following reasons.