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Compound eye of Antarctic krill as imaged by an electron microscope. A compound eye is a visual organ found in arthropods such as insects and crustaceans.It may consist of thousands of ommatidia, [1] which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color.
The structure of an animal's eye is determined by the environment in which it lives, and the behavioural tasks it must fulfill to survive. Arthropods differ widely in the habitats in which they live, as well as their visual requirements for finding food or conspecifics , and avoiding predators.
The visual systems of Chelicerata (the sister group to the remaining Arthropoda) are less well understood. It has been shown that homologs of many eye patterning genes are variably expressed in the eyes of different spider species, but the functional significance of these changes in expression is not well understood, due to lack of functional data.
The accessory visual structures (or adnexa of eye, ocular adnexa, etc.) are the protecting and supporting structures of the eye, including the eyebrow, eyelids, and lacrimal apparatus. The eyebrows, eyelids, eyelashes , lacrimal gland and drainage apparatus all play a crucial role with regards to globe protection, lubrication, and minimizing ...
Nymphalid butterflies have the simplest eye ommatidium structure, consisting of eight photoreceptor cells (R1–R8) and a tiny R9 cell organized into a different tier. [5] These "R cells" tightly pack the ommatidium. The portion of the R cells at the central axis of the ommatidium collectively form a light guide, a transparent tube, called the ...
An insect uses its digestive system to extract nutrients and other substances from the food it consumes. [3]Most of this food is ingested in the form of macromolecules and other complex substances (such as proteins, polysaccharides, fats, and nucleic acids) which must be broken down by catabolic reactions into smaller molecules (i.e. amino acids, simple sugars, etc.) before being used by cells ...
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The head capsule bears most of the sensory organs, including the antennae, ocelli, and compound eyes, along with the mouthparts. In the adult insect, the head capsule appears unsegmented, though embryological studies show it to consist of six segments that bear the paired head appendages, including the mouthparts, each pair on a specific ...