# Bilateral Symmetry in Animals **URL:** \ **Category:** Factual Questions\ **Created:** [May 14, 2001, 3:02pm UTC](https://boards.straightdope.com/t/bilateral-symmetry-in-animals/65416 "2001-05-14T15:02:07Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![don\_willard](https://avatars.discourse-cdn.com/v4/letter/d/a88e57/32.png) [@don\_willard](https://boards.straightdope.com/u/don_willard)\ **Post date:** [May 14, 2001, 3:02pm UTC](https://boards.straightdope.com/t/bilateral-symmetry-in-animals/65416/1 "2001-05-14T15:02:07Z")
I read that animals have either bilateral symmetry or radial symmetry, the latter being like in starfish. However, even round animals have five of something in them I thought, and why aren’t four limbs and head considered five-ways symmetry? Thus all animals have pent-something symmetry. Or do they? ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 14, 2001, 4:19pm UTC](https://boards.straightdope.com/t/bilateral-symmetry-in-animals/65416/2 "2001-05-14T16:19:25Z")
> [@](#): > > \*Originally posted by don willard \* > **why aren’t four limbs and head considered five-ways symmetry?** This would only be true if your head was equivalent to your arm or leg. “Symmetry” implies the components are exactly or almost exactly equivalent (except for mirror-image type reversal for bilateral organisms). A starfish’s arms are essentially alike. ---
**Author:** ![Earthling](https://avatars.discourse-cdn.com/v4/letter/e/90db22/32.png) [@Earthling](https://boards.straightdope.com/u/Earthling)\ **Post date:** [May 15, 2001, 3:46am UTC](https://boards.straightdope.com/t/bilateral-symmetry-in-animals/65416/3 "2001-05-15T03:46:24Z")
Um, consider creatures like the centipede. Lotsa legs, so even if we considered all appendages the “same,” there would be no 5-way symmetry here.