Simple Eyes

Ocellus is a type of simple eye or an optical arrangement that contains a single lens. It is named after the Celtic god Ocelus, who was venerated as a protector. It is not necessarily simple in the usual sense of the word. Human eyes and camera lenses are classified as simple, because in both cases a single lens collects and focuses light onto the retina or film.

Ocelli on head of paper wasp   Credit:  Assafn/Wikimedia
Ocelli on head of paper wasp Credit: Assafn/Wikimedia
SEM (Scanning electron micrograph) of ocelli on a hornet   Credit:  Science Photo Library/Visualphotos.com
SEM (Scanning electron micrograph) of ocelli on a hornet Credit: Science Photo Library/Visualphotos.com
Portrait of a parasitic wasp (Ophion obscuratus).  Credit:  Matthias Lenke/Flickr.com
Portrait of a parasitic wasp (Ophion obscuratus). Credit: Matthias Lenke/Flickr.co
Head of a green grocer cicada with triple occelli.   Credit:  Dr. Jeremy Burgess/Science Photo Library
Head of a green grocer cicada with triple occelli. Credit: Dr. Jeremy Burgess/Science Photo Library

Dorsal ocelli are light-sensitive organs, which coexist with compound eyes.  They are larger and more strongly expressed on flying insects like dragonflies, bees, wasps and locust where they are typically found as a triplet.   One theory is that their function is to assist in maintaining flight stability.

German wasp showing dorsal ocelli   Credit:  Francisco Javier Torrent Andres Biosphoto
German wasp showing dorsal ocelli Credit: Francisco Javier Torrent Andres Biosphoto

Spiders have several pairs of simple eyes with each pair adapted for a specific task. The forward-facing pair possess the best resolution with telescopic components to see prey at a large distance.

Apache jumping spider   Credit:  Scott Linstead/Science Source
Apache jumping spider Credit: Scott Linstead/Science Source

 

Wolf spider  Credit:  Matthias Lenke/Flickr.com
Wolf spider Credit: Matthias Lenke/Flickr.com

 

Male lobster jumping spider      Credit:  Paul/Flickr.com
Male lobster jumping spider Credit: Paul/Flickr.com
Zebra spring spider  Credit:  Matthias Lenke/Flickr.com
Zebra spring spider Credit: Matthias Lenke/Flickr.com

We are constantly learning new tricks from the natural world.  Research on the ocellus is of high interest to designers of small drones since these crafts face many of the same challenges that insects face in maintaining stability in a 3-D world.

 

 

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