Meaning of ommatidium in English:

ommatidium

Pronunciation /ˌɒməˈtɪdɪəm/

nounplural noun ommatidia/ˌɒməˈtɪdɪə/

Entomology
  • Each of the optical units that make up the compound eye of an insect.

    ‘In contrast, myriapods and chelicerates mostly lack compound eyes and the ommatidia of the few groups that have compound eyes are very different from insect/crustacean ommatidia.’
    • ‘In all these animals, the larval eye continues to exist as part of the adult eye, although the number of ommatidia in the adult compound eye far exceeds the larval quantity.’
    • ‘The retina of the compound eye is organized into approximately 3000 functional units or ommatidia, each containing eight photoreceptor cells.’
    • ‘The adult retina is composed of 750 unit eyes known as ommatidia; each ommatidium contains precisely 14 cells.’
    • ‘Postlarvae settling at the vents have reasonably normal ommatidia, with layered rhabdoms, standard crystalline cones, and faceted external corneas reflective of the zoeal apposition eye.’
    • ‘Note that in the insect ommatidium (unlike vertebrate limbs and Drosophila appendages) cells are being specified and determined individually, not as groups of cells.’
    • ‘Flies, crabs, and other arthropods have compound eyes in which many, sometimes hundreds, of individual ommatidia, or unit eyes, gather visual information.’
    • ‘These novel morphological approaches to the study of the ommatidia and the foregut ossicles may have limited application in the fossil record.’
    • ‘The normal compound eye has regular ommatidia and bristles.’
    • ‘Fleas show a transformation of the multifaceted eyes and ommatidia of most insects, replaced instead with heavily sclerotized, atypical ocelli, or ‘eyespots,’ or in some cases, a complete absence of any eye at all.’
    • ‘The compound eye is composed of ~ 800 units called ommatidia.’
    • ‘At the end of each eyestalk are some 10,000 ommatidia, or little eyes.’
    • ‘The adult retina consists of 800 identical unit eyes or ommatidia that are packed into a hexagonal array so precise that it is often referred to as a ‘neurocrystalline lattice’.’
    • ‘This paper dealt with the size of ommatidia as a function of body size in various insects.’
    • ‘In in flies we have seen examples of incorrect chiral type, incorrect rotation, symmetrical ommatidia, and ommatidia with an incorrect number of photoreceptor cells (data not shown).’
    • ‘The Drosophila retina is composed of 750 unit eyes, or ommatidia.’
    • ‘The compound eye of Drosophila is composed of hundreds of nearly identical ommatidia or unit eyes.’
    • ‘Normally, new ommatidia are added at the dorsal margin of the eye, and thus the retina gradually enlarges with growth of the eye at each successive molt.’
    • ‘The ommatidium, or ‘unit eye,’ is reiterated nearly 800 times in the compound eye.’
    • ‘During their development, some crustaceans simply enlarge the larval eye, adding ommatidia as the animal grows.’

Origin

Late 19th century modern Latin, from Greek ommatidion, diminutive of omma, ommat- ‘eye’.