Ommatidia
From Biocrawler, the free encyclopedia.
The compound eye of insects is composed of hundreds of unit eyes called ommatidia. An ommatidium contains a cluster of photoreceptor cells surrounded by support cell, and pigment cells. The outer part of the ommatidium is overlayed with a transparent cornea. The photograph to the right shows a cluster of photoreceptor cells from a single ommatidium from Drosophila melanogaster (magnified 400X). It is about 85 μm in length and 5-10 μm in diameter. The nucleus and the rhabdomere from a photoreceptor cell are visible.
superposition eye crossection - low light condition top with separating pigments contracted, so that the light reaches over many ommatida the nerve, bright condition below with pigments expanded
ommatidia of Antarctic krill eye - click for higher resolutions
