‘A disembodied head walking about the sea floor on its lips’: Scientists finally work out what a starfish is


Scientists have discovered starfish are essentially heads with feet.  (Image credit: Gerard Soury/Getty Images)

Scientists have finally solved the puzzle of starfish’s unique bodies. As it turns out, sea stars and other echinoderms are essentially walking heads with little to no body. 

Echinoderms — sea stars, sea urchins, sea cucumbers, and their relatives — have unique bodies that have long puzzled evolutionary biologists. These animals evolved from bilateral organisms — those that have two symmetrical sides — but somehow they evolved a radial body plan, meaning their body parts are arranged around a central axis. In the case of adult sea stars, five (or more) arms emanate from a central structure.