|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
|
Fig. 2. (A) Schematic drawing of an apposition compound eye. The aperture (A) is
defined by the diameter of a single corneal lens (c). Pigment (p) between the
crystalline cones (cc) isolates ommatidia optically. Rhabdom (rh) length (l)
and diameter (d) influence sensitivity; f, focal length. (B) Schematic drawing
of a superposition compound eye. The clear zone (cz) interspaced between the
crystalline cones and rhabdoms allows light entering through a large number of
facets to be focussed on one rhabdom. This enlarges the aperture by factor of
up to 1000. (C) Superposition eye of Deilephila elpenor (photo
courtesy of Pär Brannström). cz, clear zone; re, retina. (D)
Schematic drawings of the structure of the rhabdom of D. elpenor
(adapted from Schlecht et al., 1978). B, basement membrane; Rh, rhabdom; Tr,
tracheal tapetum, N, nucleus. Receptors 1 and 2 are blue- or UV-sensitive;
receptors 3–9 are green-sensitive. (E) About 1000 facets of D.
elpenor that build the superposition aperture glow when the eye is
illuminated and viewed from the same direction. Photo courtesy of Michael
Pfaff. (F) Random arrays of ommatidial types in the crepuscular hawkmoth
Manduca sexta (redrawn from White
et al., 2003). White circles, ommatidia with all three receptor
types; black circles, ommatidia with green and blue receptors; grey circles,
ommatidia with green and UV receptors. Arrows show the eye horizon. (G) The
effect of filtering in the long fused rhabdom of a dark-adapted nocturnal
hawkmoth. The broken lines represent the sensitivities that would result from
self-screening, if the long photoreceptors of D. elpenor had open
rhabdoms. The solid lines represent the sensitivities resulting from filtering
in the fused and tiered rhabdom.
|
