Gonodactylus
Premium Member
Yes, juvenile Odontodactylus scyllarus are cute, but that is not the reason I have posted this photo. This shot nicely demonstrates the acute zone of the mantis shrimp's eye where the photo receptors (ommatidia) are all oriented in the same direction providing maximum information about the distance, color, polarization and movement of the target. Over most of the eye, only a few ommatidia are pointing at the same location. We see this in the form of the pseudopupils, the black spots produced when the receptor is pointing at the camera or your eye and no light is reflected back. If the eye is looking above or below the the plane formed by the mid-band, we see just two small pseudopupils. If the ommatidia in the mid-band are pointing at your eye, we see three sets of pseudopupils. Around most of the mid-band, only a handful of receptors are aimed at the target and the pseudopupils appear as slits. However, in a small region in the front of the eye more of the ommatidia are aliened together with the resulting pseudopupils appearing as large dark blotches. When an animal is particularly interested in an object, both eyes are brought to bare on the target and we see six large sets of pseudopupils. Because the eyes are usually in motion independently scanning the visual field, we usually don't see the acute zones of both eyes simultaneously. However, in this case, I placed another stomatopod just below the camera lens. The cavity resident became very interested in the intruder, focused both eyes on the opponent for about a second and then attacked.
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