Mantis shrimp vision

[Gonodactylus]

Many of you who frequent this site know that stomatopods have remarkable vision. In a recent book by Land and Nilsson called "Animal Eyes", there is a brief description of Odontodactylus vision that I found clear and insightful. I've copied part of it here in case you are interested in what your animal is looking at when you are gazing into its eyes.


"Their eyes are basically compound eyes of the ordinary apposition type, which provide an erect two-dimensional image. However, stretching more or less horizontally across each eye is a band of enlarged facets, 6 rows wide. This mid-band, which has a field of view only a few degrees in width, contains the animals' extraordinary color vision system. This consists of four of the mid-band rows (the other two subserve polarization vision) and in each row the receptors are in three tiers. Each of the 12 tiers contains a different visual pigment, giving the animal the potential for dodeca-chromatic color vision, with 8 pigments covering the visible spectrum, and a further four in the ultraviolet. In adopting this impressive system, however, the mantis shrimps have set their eye movement system a daunting task. The outer parts of the eye operate as normal compound eyes - and are subject to the kinds of image stability considerations discussed earlier. The mid-band, however, has to move or it will not be able to register the color of objects in the environment outside a very narrow strip. The result of this visual schizophreneia is a repertoire of eye movements unlike anything else in the animal kingdom,. In addition to "normal' eye movements (fast saccades, tracking and optokinetic stabilizing movements) there is a special class of frequent, small (c. 10 degree) and relatively slow (40 degree/sec) movements, which give the animal a strange inquisitive appearance perhaps because they resemble human saccades in their frequency of occurrence. They are, however, not saccades, which are much faster. These movements are typically at right angles to the band and the only plausible explanation is that they are the scanning movements the band uses to pick out relevant colored features in the surroundings."

Sorry, but I really get excited by stomatopod vision!

Roy

 

[jedimpt]

So does eye movements mean that my mantis isn't just fascinated by me and my god-like presence over his little world?

 

[dc]

Sorry, but I really get excited by stomatopod vision!

Hmmmm, does your wife know this?

They are just amazing creatures aren't they?

 

[kalim]

i'll agree.

most people are fascinated by the unique hunting capabilities of the mantis shrimps, but in fact it is probably (IMO) their eyes that sets them very far apart from anything else.

i saw a recent book that hypothesized that the cambrian (?) explosion (where biological diversity suddenly increased dramatically) was the result of the "invention" of eyes....if so, then mantis shrimps are the penultimate result of that long line of experiments, and represent the "height" of evolution so far in terms of providing awesome vision.

and yes, i think the "inquisitive" look by mantis shrimps seem to be because of these eye movements.

 

[jedimpt]

It is the eyes that give the mantis personality. They have no other form of "facial" expression. Given that they tend to be shy, cautious creatures, and the way their eyes follow its target, they seem get a curious look. I quess we tend to give them and other fish human traits. Just like those cute puffers who are always big eyed and smiling at me whenever I go to see them at the LFS!

 

[jedimpt]

Roy, Great Article

Roy, Great Article

By the way Roy, thanks for attempting to enlighten neandrethals like me and my friends. Now I have another detail to give my buddies when they come see my tanks. Not that they will really care, they just like to see it eat something. But they will learn while they are there. This I COMMAND!:strooper:

 

[RogueCorps]

Very interesting Dr. Roy,

I had thought that the red-light trick for night critter-viewing wouldn't work on stomatopods because of their incredible vision. I had wondered if they might also see into the infrared spectrum and would be able to see the night-shot LEDs from my sony camcorder. I guess not.

She does seem to still notice me when I try to use night-vis on her... Maybe the light from the eyepiece is giving me away.



-Rogue

 

[Gonodactylus]

The ability to see red in gonodactylids if about the same as ours. We do a fair amount of infrared observation and videotaping and I have noticed that infra-red LEDs that emit a red glow that I can see also causes the stomatopods to respond. Your observation of light being emitted from the viewing screen or eyepiece is also a good one. This can be a real problem to the point that in some experiments I have to tape over any possible source of visible light,.

One of the things that fascinates me about stomatopods is that some species will actually maniulate objects to view them. I can't think of any other invertebrate that will do this.

Roy

 

[kalim]

" One of the things that fascinates me about stomatopods is that some species will actually maniulate objects to view them. I can't think of any other invertebrate that will do this."

can you elaborate on this? i would think lots of invertebrates (including insects) manipulate objects when examining them.

 

[Agu]

Dr Roy,

You lost me on most of that, but the "relatively slow (40 degrees/second)" caught my eye. (sorry for the bad pun ). Does this result in the mantis "examining" us for extended periods when not threatened ? Sounds like their extraordinary vision has the drawback of needing longer exposure to fully view their environment.

Agu

 

[Gonodactylus]

This is a difficult comparison to make. The stomatopod eye actually has a much greater field of vision than ours basically detecting movement all around the animal. However, the area of acute vision equivalent of our fovea is a stripe only a few degrees wide. When you look at a scene, your eye flicks around the image recording areas of interest. The stomatopod eye works more like a bar scanner. The speed that the eye scans is slower, but the amount of information taken in is considerable.

Roy