Natures wonders: Manis shrimp use polarized light (Introduction)

by David Turell , Wednesday, July 13, 2016, 02:26 (3054 days ago) @ David Turell

Apparently by rolling their eyes in many directions, a phenomenon not fully understood:-http://phys.org/news/2016-07-mantis-shrimp-eyes-vision.html-"PhD student Ilse Daly, from the Ecology of Vision research group in the from the University of Bristol's School of Biological Sciences, found the eye-rolling behaviour of mantis shrimp helps them see the world around them.-"Mantis shrimp are able to see the polarization of light, and by rolling their eyes they actively improve the polarization contrast of objects in their marine environment.-***-"They can use 12 different colour channels (we use only three), and can see the polarization of light. But the eye movements of mantis shrimp have always been something of a puzzle.-"'Intuitively, a stable eye should see the world better than a mobile one, but mantis shrimp seem to have found a different way to see more clearly."-"The visual world of the mantis shrimp is staggeringly complex. Now add to that the ability to actively enhance their vision using eye movements -The article abstract:-"Gaze stabilization is an almost ubiquitous animal behaviour, one that is required to see the world clearly and without blur. Stomatopods, however, only fix their eyes on scenes or objects of interest occasionally. Almost uniquely among animals they explore their visual environment with a series pitch, yaw and torsional (roll) rotations of their eyes, where each eye may also move largely independently of the other. In this work, we demonstrate that the torsional rotations are used to actively enhance their ability to see the polarization of light. Both Gonodactylus smithii and Odontodactylus scyllarus rotate their eyes to align particular photoreceptors relative to the angle of polarization of a linearly polarized visual stimulus, thereby maximizing the polarization contrast between an object of interest and its background. This is the first documented example of any animal displaying dynamic polarization vision, in which the polarization information is actively maximized through rotational eye movements."-The summary: -"In summary, the dynamic polarization vision system of mantis shrimps is yet another example of an exquisite and unique adaptation to visual perception in these crustaceans and such findings could prove useful for developing bio-inspired technology in the field of polarization cameras and image processing. However, there are still a number of questions about this remarkable polarization vision system that remain to be investigated, such as how do these animals determine which set of receptors (dorsal or ventral) to align with the stimulus?; how is the information processed downstream within the optic neuropil and beyond?; and how, if at all, is information combined from the two eyes?" (my bold)-Comment: this is a highly complex visual system, which raises the usual issue. How would chance possibly develop this? It won't, and it is difficult to see that advanced planning is not needed. Back to saltation.