Moderators: rjlittlefield, ChrisR, Chris S., Pau
On quick search for snail eye resolution ...Cyclops wrote:I wonder just how much a snail does see, or do they just perceive light and dark?
--RikThe structure of the eye does not provide detailed vision, they rather function as directional light sensors that give the snail an orientation towards light sources.
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It appears that the eyes of apple snails are rather optimized for optical sensitivity (night vision!) rather than for high detail vision. In fact, two mechanism are used in the apple snail eye to increase sensitivity to light: the eyes are relatively large with a large lens (large eyes= more light captured) and the light sensitive cells (rhabdoms) are grouped and connected with the same neuron (pooling of signals or neural summation = higher sensitivety, but lower resolution). It has even been suggested that the optical sensitivity of the apple snail approaches that of the nocturnal spider Dinopis subrufus (Blest and Land, 1977).
The spatial resolution of the eye, however, is estimated to be around a poor 44 pixels (SEYER, J.O. et al. 1998).
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One can conclude that the eyes of apple snails are suitable to find light and dark area's within their invironment, even at night, but that their overal vision in the sense of image quality is rather poor.
Ah thats interesting, but of course an Apple Snail is an underwater snail (had one in my fishtank recently with disastrous results!), so their eyes would need to be more sensitive I imagine.rjlittlefield wrote: On quick search for snail eye resolution ...
http://www.applesnail.net/content/anatomy/senses.php--Rik
It appears that the eyes of apple snails are rather optimized for optical sensitivity (night vision!) rather than for high detail vision. In fact, two mechanism are used in the apple snail eye to increase sensitivity to light: the eyes are relatively large with a large lens (large eyes= more light captured)
One can conclude that the eyes of apple snails are suitable to find light and dark area's within their invironment, even at night, but that their overal vision in the sense of image quality is rather poor.
