ommatidioita

Ommatidioita, also known as ommatidia (singular: ommatidium), are the fundamental functional units of compound eyes found in insects and many crustaceans. Each ommatidium is a microscopic, self-contained visual unit, and a compound eye is essentially a mosaic of hundreds or thousands of these individual units.

Structurally, an ommatidium typically consists of a transparent outer surface called the cornea, which acts as a lens. Beneath the cornea is a crystalline cone, also acting as a lens, and a light-sensitive structure called the rhabdom. The rhabdom is formed by photoreceptor cells, which contain light-sensitive pigments. Each ommatidium is surrounded by pigment cells that help to isolate it from its neighbors, preventing light from scattering between units.

When light enters an ommatidium, it is focused by the cornea and crystalline cone onto the rhabdom. The photoreceptor cells within the rhabdom then convert this light energy into electrical signals. These signals are processed and transmitted to the insect's nervous system, ultimately contributing to the formation of the overall image perceived by the compound eye.

Each ommatidium typically captures a small portion of the visual field. The brain then combines the information from all the ommatidia to construct a complete, albeit often pixelated, image. This arrangement allows for a wide field of vision and excellent detection of movement, which are crucial for survival in many arthropods. The specific structure and number of ommatidia can vary significantly between different species, correlating with their visual needs and ecological niches.