Ocellus | anatomy | Britannica (original) (raw)

Learn about this topic in these articles:

Assorted References

• types of bilateral nervous systems
  • 
    In nervous system: Simple bilateral systems
    The eyes, or ocelli, may occur as a pair situated anteriorly or may be scattered abundantly over the head region depending on the species. Short optic nerves connect the eyes with the brain.
    Read More

anatomy of

insects

• 
  In insect: Eyes
  …two kinds, simple eyes, or ocelli, and compound eyes. In the adults of higher insects both types are present. The visual sense cells are derived from the epidermis, as are those of other sense organs, and are connected to the optic ganglia (a part of the brain) by sensory axons.…
  Read More

• grasshoppers

  • 
    In grasshopper
    …in the simple eyes (or ocelli). Although most grasshoppers are herbivorous, only a few species are important economically as crop pests.
    Read More

• lepidopterans

  • 
    In lepidopteran: Head
    …very small simple eyes (ocelli), which have limited light-sensing ability but do not form an image.
    Read More

• cnidarians

  • 
    In cnidarian: Nervous system and organs of sensation
    Light-sensitive ocelli (external patches of pigment and photoreceptor cells organized in either a flat disk or a pit) occur in some medusae of each of the three classes that possess this stage. Such sensory structures are closely associated with a nerve net.
    Read More