Structure of Visual organs (Compound eye) of Cockroach

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Structure of Visual organs (Compound eye) of Cockroach 

Compound eyes, also known as simple eyes or ommatidia, are found on the lateral sides of a cockroach's head. They are each composed of approximately 2000 hexagonal units and resemble a black, kidney-shaped structure. A compound eye's ommatidiums each contribute to the image of an item that lies along its optical line. 


Because cockroaches are nocturnal creatures, they are most active at night.These kinds of organisms create blurry images by the overlaying of many images.

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The visual structures seen in arthropods are called compound eyes.
Compound eyes, also known as simple eyes or ommatidia, are found on the lateral sides of a cockroach's head. They are each composed of approximately 2000 hexagonal units and resemble a black, kidney-shaped structure.
A compound eye's ommatidiums each contribute to the image of an item that lies along its optical line.
The brain then combines all of the produced images to create a single image.
Mosaic vision is the term for this kind of vision.

A pair of compound eyes are located on the head, close to the vertex's sides. The kidney-shaped, black compound eyes are sessile. A transparent cornea with 2000 hexagon-shaped corneal facets covers each eye.

An ommatidium is represented by each corneal facet. Thus, every compound eye contains 2000 ommatidia. A structural and functional component of the compound eye is the ommatidium.

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Ommatidium structure: The corneal facet resembles a biconvex lens. Two comeagen cells, located directly below the facet, secrete this corneal lens. Beneath the comeagen cells are four cone cells, commonly known as vitrelles. A crystalline cone that is located in the center of the cone cells is secreted by them. Just below the cone cells, there is a rhabdome surrounded by seven retinal cells. The retinal cells secrete the rhabdome. There are 14,000 retinal cells in each compound eye, and they are all located on a basement membrane. An optic nerve is made up of all 14,000 nerve fibers, each of which is produced by a retinal cell.



The dioptric portion is made up of the cornea, comeagen cells, and cone cells. Similar to this, the receptor portion is made up of the retinal cells and the rhabdome. Pigmented sheaths aid to maintain the ommatidium's optical isolation. There is a retinal pigmented sheath covering the dioptric portion. The cockroach's pigmented sheaths are not retractable. As a result, the ommatidia have permanent optical isolation. Other insects have colored sheaths that are contractile and shrink in low light. Thus, in low light, optical isolation is lost.

Function of the compound eye: In insects, two kinds of pictures are often created, namely. Opposition image: It forms in light conditions ranging from moderate to bright. Another name for it is a mosaic image. In the intense light, the pigmented sheaths enlarge to create an optical isolation for the ommatidium. Within one ommatidium, the image of a single portion of the object is generated. It is therefore a unique image. Only mosaic vision develops in cockroaches. Overlay picture: It forms at night and under low light. The sheet that is colored is contracting. Thus, there is a loss of optical isolation. The image is not clear. A single portion of the object's picture is produced in numerous nearby ommatidia.





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