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The horned frog has a large light-collecting pupil for night vision. like many snakes and reptiles, the tokay gecko has a stenopeic pupil that shuts down to two tiny circles in bright daylight. the australian female net-casting spider has a very large lens to enhance night vision. the flounder has a beautiful filigree-like pupillary flap, perhaps to help camouflage it as it hides in the sand. the octopus has an unusual square-shaped pupil. the vine snake's pupil is irregularly shaped. nocturnal snakes have slit pupils and infrared sensing pits around their jaws so that they can see in the dark.