• Question: Why is there no mammal with green fur? Green is a good camouflage color, and nonmammals (for example, frogs, snakes, and birds) do come in green. Why not mammals?

    Asked by brittanym to Cathal, Daphne, Darren, Jon, Katherine on 13 Mar 2012. This question was also asked by liverpoolrules.
    • Photo: Katherine Haxton

      Katherine Haxton answered on 12 Mar 2012:

      I once saw a photo of a sloth and it had green fur because algae grew on it! Problem with green camouflage is that it wouldn’t be that much use in the winter if all of the green plants died back.

    • Photo: Darren Logan

      Darren Logan answered on 13 Mar 2012:

      Awesome question.

      I was in Costa Rica last year and, like Katherine says, saw some sloths that camouflage themselves with green algae. This is a really cool way of getting around a problem that mammals have: they only have one type of pigment cell called a “melanocyte” that produces a couple of types of pigment (coloured chemicals they can make in their fur and skin): red/yellow (called phaeomelanin) or brown/black (called eumelanin). So most mammals come in variations of these colours (or white, which is the lack of a pigment).

      Nonmammals have lots of different types of pigment cells that produce lots of different pigments. Including red, yellow, orange, silvery, reflective, blue and black. By stacking these cells on top of each other you can get all sorts of colours including green.

      So this is explains how the difference of colours work, but we don’t yet know why mammals lost all these other types of cells.

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