How stomatopods judge distance

Gonodactylus

Premium Member
Ever wonder how how a stomatopd knows how far away an object is that it is trying to spear? This image of a juvenile Lysiosquillina sulcata looking out of its burrow provides some of the answers. Each eye is made up of hundreds of indivdiual optical units called ommatidia. Each ommatidium is like a telescope looking out at a small piece of the world. When light enters an ommatidium "on axis" (straight down the barrel), the light is absorbed and is not reflected back. The ommatidium appears black. This is analogous to looking into the pupil of a human eye, No light is being reflected back and the pupil appears black. Hence, we call these black spots on the surface of a stomatopod eye "pseudopupils".

The pattern of pseudopupils in a stomatopod eye can tell us where the various ommatida are aimed. When I took this picture, the eye on the left was pointed in the direction of the camera lens. You can see a cluster of dark spots in the center of the upper and lower hemispheres of the eye as well as another group of dark spots in the center. This means that some of the ommatidia in the mid-band of the eye as well as as groups in the upper and lower part of the eye are pointing right at the camera.

The eye on the right is looking to the right. Only a few ommatidia on the extreme periphery are pointing towards the camera. Notice that the surface of the eye near the center is concave. The ommatidia (in spearers) generally point outward perpendicular to the surface. That means that objects located directly in front, but close to the eye will be seen by ommatidia close to the midband; objects further away but in the same direction will be seen by ommatidia further from the midband. Alternatively, if I moved my camera closer to the eye, the pseudopupils would be seen closer the the midband. The ommatida of the midband (made up of six rows of ommatidia) all look out on the same equatorial plane.

Just as you tell how far objects are away by using binocular vision analyzing how much your eyes are pointing toward the mid-line, the stomatopod can judge distanceby comparing which ommatidia are focused on the same spot. The difference is that when the stomatopod is looking intently at an object using both eyes, it has six regions of the eyes brought to bare on the target giving it hexnocular vision.

Roy

5463Lsjuvenileeyes1small.jpg
 
Awesome write up, Roy. I often wondered how they judged distance and how their eyes worked in general. I had noticed the Ommitidia before, but had no idea what they are.

Very interesting.
 
that is a gorgeous eye ball shot! amazing detail. I love reading these stomato-info-posts of yours. I learn something new in every single one.
 
Very interesting read Dr. Roy. Thanks so much for posting this as I've wondered for a while how their eyes actually work.
 
Thanks for this Dr Roy, this explains their vision in a much simpler way than in other places I've read. Very interesting!
 
I'm new to the forum but I had a mantis show up 10 years ago after 10 fish disappeared one by one over a month. I had to remove all the live rock to get him out of the tank. Got interested in them after that and read a lot. I believe I have read that the mantis shrimp has 21, and later in another read 23 types of sensors in their eyes. Like we have rods to see black and white and cones to see color the mantis have at least 21 types in their eyes. They see way into the infrared and ultraviolet and who knows what else. I also believe they use these to identify their mates in the deep darkness. Am I remembering that all right?
Len
 
Len,

There are up to 16 visual pigments that respond from 300 to 700 nm. That is not into the infrared, but it is the broadest spectral sensivity of any known animal.

Roy
 
<a href=showthread.php?s=&postid=12590326#post12590326 target=_blank>Originally posted</a> by Gonodactylus
Len,

There are up to 16 visual pigments that respond from 300 to 700 nm. That is not into the infrared, but it is the broadest spectral sensivity of any known animal.

Roy

Does that mean that where the human eye sees the three primary colors Red, Blue and Green, and makes all the other colors we see from the combination of these three colors, that Mantis shrimp see in 16 "primary colors"?

Thanks
David
 
Roy, do you think they could detect the changes in UV radiation striking the Earth as the sunspot cycle changes the blackbody radiation? I.e. Do you think they can tell it is "brighter"?
 
If it were an instantaneous change from minimum to maximum, perhaps, but not if the change is gradual over even minutes let alone years.

Roy
 
Dr. Roy, what would be the average distance a stomatopod could see outside its tank? I'm just looking for a general answer, say the thickness of a ten gallon glass tank with clean glass out and inside. I always wonder if my stomatopods can see me before I enter the room.
What about in the ocean?
 
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