I'm trying to identify the basic biological mechanisms for sight.

Could you help me with identifying any organism that has the most basic ability to see objects?

Most importantly, creatures like dogs, cats, insects are able to not just see light, but are also able to identify objects and other living beings. I feel that an organism could be classified as "being able to see" if it can identify objects and movement and use its "visual sensory organ" to help it move around, locate food, identify species of animals, differentiate between living and non-living and escape predators if any.

Even if an organism can see just black and white or the most basic perception of sight, it would qualify for what I'm searching for. Is there any such known organism that has such a basic visual perception and has the way its eye+brain perceives images, been studied?

I'm not referring to the kind of "photosensitivity" that plants have. Detecting the presence and direction of light is not sufficient.

  • $\begingroup$ Could the downvoter please explain why this is a bad question? $\endgroup$ – Nav Aug 23 '17 at 11:30
  • $\begingroup$ Here is my explanation why someone would downvote such a question: having taught evolution for more than 20 years, I'm always annoyed by "less evolved" (or least) and "more evolved". That simply doesn't make any sense in evolution. It's a medieval concept, a scala naturae, persisting in the 21st century. That being said, this question has no answer because it's based on a wrong (or nonexistent) assumption. If that's the reasoning behind the downvote we'll probably never know. $\endgroup$ – user24284 Aug 23 '17 at 12:59
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    $\begingroup$ "less evolved" does not mean anything. Instead you can ask "What was the first lineage to evolve the ability to detect electromagnetic waves?" $\endgroup$ – Remi.b Aug 23 '17 at 14:49
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    $\begingroup$ It doesn't make sense for an organism to be "less evolved" because every organism has been equally subjected to billions of years of evolution. $\endgroup$ – sterid Aug 23 '17 at 15:43

Which is the least evolved organism that can see?

The term less evolved does not mean anything. Instead one can ask

Which lineage was the first to evolve the ability to see?

And by "see" of course, I mean detect electromagnetic waves. Seeing does not imply color vision and does not imply accurate vision.

It will be hard to tell really which lineage came up with vision first. But I am sure you'll be interested to know that some cyanobacteria are able to detect electromagnetic waves (reviewed in Nilsson and Colley 2016).

  • $\begingroup$ Thanks Remi. You've linked to an excellent article. They conclude that "Both photoreception and vision thus have multiple origins", and "The ‘simplest’ organisms with real eyes are warnowiid dinoflagellates". $\endgroup$ – Nav Aug 23 '17 at 16:25

I remember from Zoology lessons (on University) that flatworms (Platyhelminthes) already can detect light. I am not sure if this is the least evolved organism though. Do you mean animal or really organism. Plants and algae are also organisms in which light is very import for them to detect.

  • $\begingroup$ Thanks. I do not just mean the ability to sense if light is present or not. I'm asking about the capability to see objects/beings and interpret them as objects/beings. $\endgroup$ – Nav Aug 23 '17 at 11:04
  • $\begingroup$ Alright, with your definition flatworms are not the ones you are looking for. See here about their eyes, they detect light dark only. Your question becomes a bit more difficult when added "brain" and "perception of images", because what do you consider a brain? Do molluscs have a brain? Do they perceive images? How do we know?? $\endgroup$ – user35628 Aug 23 '17 at 11:16
  • $\begingroup$ That's why I asked "has that visual perception and the way its eye+brain perceives images been studied?". btw, I'm not the downvoter. $\endgroup$ – Nav Aug 23 '17 at 11:30
  • $\begingroup$ I don't know why someone down votes your question, some people do this without any reason or explanation. I will try to neutralize with up vote, but don't know how long it will stronghold. $\endgroup$ – user35628 Aug 23 '17 at 11:37
  • $\begingroup$ @Nav see objects/beings and interpret them as objects/beings is rather undefined. A bacteria that can sense light and react to it can be argued to being able to interpret the presence of objects. $\endgroup$ – Remi.b Aug 23 '17 at 16:27

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