What is "eyespot"

n. 1 (context biology English) Any of various primitive light-sensitive organs or regions in many diverse organisms. 2 An eye-like marking on the tail of a peacock or the wing of a butterfly. 3 (context botany English) Any of a group of fungal infections of grasses that are characterized by oval spots.

n. an eyelike marking (as on the wings of some butterflies); usually a spot of color inside a ring of another color [syn: ocellus]

Eyespot is an important fungal disease of wheat caused by the necrotrophic fungus Tapesia yallundae (syn: Pseudocercosporella herpotrichoides; W-type [anamorph]; Oculimacula yallundae) and Tapesia acuformis (syn: Pseudocercosporella herpotrichoides; R-type [anamorph]; Oculimacula acuformis). It is also called Strawbreaker. Eyespot is more severe where wheat is grown continuously and when the weather is cool and moist. Treating crops against eyespot with fungicide costs millions to farmers and is complicated by the pathogen becoming resistant to the more commonly used fungicides. Severe cases of the disease can reduce yield by up to 40%. It is most common in temperate regions such as North and South America, Europe, Australia, New Zealand and Africa.

An eyespot (sometimes ocellus) is an eye-like marking. They are found in butterflies, reptiles, cats, birds and fish.

Eyespots may be a form of mimicry in which a spot on the body of an animal resembles an eye of a different animal to deceive potential predator or prey species; a form of self-mimicry, to draw a predator's attention away from the most vulnerable body parts; or to appear as an inedible or dangerous animal. In larger animals, eyespots may play a role in intraspecies communication or courtship – the most well-known example is probably the eyespots on a peacock's display feathers. Eyespots are not necessarily adaptations, but may in some cases be spandrels, accidental artefacts of pattern formation.

The morphogenesis of eyespots is controlled by a small number of genes active in development of a wide range of animals, including Engrailed, Distal-less, Hedgehog, and the Notch signaling pathway.

Eyespot can mean:

• Eyespot (mimicry), a color mark that looks somewhat like an eye
• Eyespot, a sensory organ of invertebrates
• Eyespot, a type of eye in some gastropods, a part of sensory organs of gastropods
• Eyespot apparatus, a photoreceptive organelle found in the flagellate (motile) cells unicellular photosynthetic organisms

In diseases:

• Eyespot (wheat), a disease of wheat.
• Groundnut eyespot virus, a plant pathogenic virus

Fish species:

• Eyespot gourami (Parasphaerichthys ocellatus)
• Eyespot puffer ( Tetraodon biocellatus)
• Eyespot skate (Atlantoraja cyclophora)