The (male) Fiddler Crab is a famous example of an animal whose morphology exhibits neither mirror nor radial symmetry:

enter image description here (Image source)

List of animals featuring external asymmetry is a Wikipedia article showcasing a few more animals with this property.

Is there a comprehensive list of all such animals that have been described?

  • $\begingroup$ Many(all?) sponges are asymmetrical. $\endgroup$
    – biogirl
    Commented Jun 26, 2014 at 2:22
  • $\begingroup$ I don't think that there is a list yet for all but I could probably help you with a few if that is ok. $\endgroup$ Commented Jun 26, 2014 at 7:19
  • $\begingroup$ Any that are not on the Wikipedia list would already be helpful :) $\endgroup$
    – user6890
    Commented Jun 26, 2014 at 17:28
  • $\begingroup$ I am asymmetrical. My right hand is bigger than my left. :) $\endgroup$
    – J. Musser
    Commented Jul 18, 2014 at 23:21
  • $\begingroup$ There is a Wikipedia page called "list of animals featuring external asymmetry" $\endgroup$
    – Remi.b
    Commented Dec 3, 2014 at 3:27

1 Answer 1


1) Pareas iwasakii has asymmetric mandibles. A few more examples of asymmetric snakes (reference)

enter image description here

Pareas iwasakii skull

2) Camels have an asymmetric penis (reference)

3) You could find quite a few in this article titled Animal asymmetry

Hope that helps. I am sure there are more but these are some I could find.


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