A new analysis delves into the details of brittle star locomotion.

Other animals, including jellyfish and sea anemones, have bodies that can be divided into matching halves in multiple ways. This is called radial symmetry. Brittle stars fit into this category; their bodies can be divided into matching halves five different ways.

 

Symmetry influences how an animal moves about. Animals with bilateral symmetry, like humans, have bodies specialized to move in one direction — forward. Many animals with radial symmetry don't move or do so slowly. When they do travel, most of these animals do so in a direction determined by their body's central axis, defined by the location of their mouths. Think of a jellyfish moving up and down in the water column.