Perception 2

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…light varies greatly. Most mammals cannot distinguish different colours, whereas some birds can detect the polarization of light. Many insects can see light in the ultraviolet range, which is beyond our spectrum, while snakes can form images of infrared radiation (radiant heat). In many animals, light is also detected by another organ, the pineal body, which 'sees' light filtering through the skull, and measures the length of the day to keep track of the seasons.