Two white-lipped snails on moss, one with a plain shell and the other with a striped shell


Polymorphism means 'many forms' and can be exhibited in a variety of ways. A truly polymorphic species has individuals of notably different appearance living in the same area. Army ants, which have workers of different sizes in the same nest, are therefore polymorphic as are adders which can have a zig-zag pattern on their skin or be uniform black in colour. If the difference is between males and females of a species, as with peacocks and peahens, it's sexual dimorphism rather than polymorphism.

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