Eye is on the Sparrow

A "camera eye" not made with any cells--just organelles, complete with a "lens and retina." Credit: Hoppenrath and Leander
A “camera eye” not made with any cells–just organelles, complete with a “lens and retina.”

From our Easily Amazed Department: a July 1, 2015 detailed piece of sub-cellular anatomy finds in a particular dinoflagellate–a motile predatory alga type consisting of a single cell per individual–this remarkable enormous “eyespot” that is far more than the dot of phototaxic pigment we learned about in in Biology 101 that you saw something like Euglena for modifying the flagellum to vaguely move towards the light for improved photosynthesis.

This is a true “camera eye”, not a simple eyespot, and so like an animal eye it was once thought to be a digestive remnant of something this dinoflagellate had ingested.

In this case, the eye-covering “cornea” and light-refracting “lens” are made up of inter-connecting mitochondria, that you probably learned about as the “powerhouse” ATP generating parts of a typical cell.

The lower portion that is red in this illustration (Credit: Hoppenrath and Leander) consists of plasmids, whose general purpose typically is to convert light to energy (like chloroplasts.) And these, ostensibly, convey chemically (since there are no nerves) a message to the organism to–well, it is not known what or how this happens.

Dinoflagellate “eyes” then predate animal “camera eyes” of even the most primitive vertebrates by many hundreds of million years, solving the same “problem” with a remarkably similar solution from molecular parts on hand.  The technical name for this duplication of solutions is “convergent evolution.”

Having a term for it, I suppose, helps; but it leaves a lot of questions unanswered, even as I marvel at the answers living matter finds to carry on.

Plankton’s ‘eye’ made up of organelles, study suggests – Technology & Science – CBC News

Single-Celled Planktonic Organisms Have Animal-Like Eyes, Scientists Say | Biology | Sci-News.com

Single-celled predator evolves tiny, human-like ‘eye’

Human-like ‘eye’ in single-celled plankton: Mitochondria, plastids evolved together — ScienceDaily

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Fred First holds masters degrees in Vertebrate Zoology and physical therapy, and has been a biology teacher and physical therapist by profession. He moved to southwest Virginia in 1975 and to Floyd County in 1997. He maintains a daily photo-blog, broadcasts essays on the Roanoke NPR station, and contributes regular columns for the Floyd Press and Roanoke's Star Sentinel. His two non-fiction books, Slow Road Home and his recent What We Hold in Our Hands, celebrate the riches that we possess in our families and communities, our natural bounty, social capital and Appalachian cultures old and new. He has served on the Jacksonville Center Board of Directors and is newly active in the Sustain Floyd organization. He lives in northeastern Floyd County on the headwaters of the Roanoke River.

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