Did you know that 96% of animal species have eyes in one form or another? But when left in complete darkness, we are all left totally blind, or are we? For us humans, yes. We can only see when there is some source of light. Even cats, known to have good night vision, cannot see in absolute darkness. But many other animals can still see in pitch black.

Photo used in this episode is from the  Passivhaus Institut, Germany – http://www.passiv.de and is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported license https://creativecommons.org/licenses/by-sa/3.0/