ISSN:
1432-1351
Keywords:
Compound eye
;
Optics
;
Crustacea
;
Evolution
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Compound eyes of the decapod shrimp Gennadas, the hermit crab Dardanus, and the syncarid crustacean Anaspides are studied histologically and with optical experiments. The results demonstrate that these three crustaceans all have refracting superposition eyes. The conclusion is based on the following observations: 1. There is a wide clear-zone, which allows for a superposition image to be formed. 2. Dark-adapted eyes display a large eye-glow, and the ommatidia are not optically isolated. 3. The crystalline cones have the shape typical for refracting superposition eyes, and they contain the required lens-cylinder gradient of refractive index. Euphausiids and mysids were previously thought to be the only crustaceans with refracting superposition eyes, whereas the species investigated here were assumed to have reflecting superposition eyes (decapod shrimps) or apposition eyes (hermit crabs and syncarids). The present findings increase more than twofold the number of crustacean groups that are known to have developed refracting superposition optics. It also provides insight into the evolutionary mechanisms that may have led to the development of this type of imaging optics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00192407
