Related Experiment Video
Updated: May 10, 2026

A Protocol for Bioinspired Design: A Ground Sampler Based on Sea Urchin Jaws
Published on: April 24, 2016
Cambrian spiral-plated echinoderms from Gondwana reveal the earliest pentaradial body plan
Andrew B Smith1, Samuel Zamora
1Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK. a.smith@nhm.ac.uk
Abstract:
Echinoderms are unique among animal phyla in having a pentaradial body plan, and their fossil record provides critical data on how this novel organization came about by revealing intermediate stages. Here, we report a spiral-plated animal from the early Cambrian of Morocco that is the most primitive pentaradial echinoderm yet discovered. It is intermediate between helicoplacoids (a bizarre group of spiral-bodied echinoderms) and crown-group pentaradiate echinoderms. By filling an important gap, this fossil reveals the common pattern that underpins the body plans of the two major echinoderm clades (pelmatozoans and eleutherozoans), showing that differential growth played an important role in their divergence. It also adds to the striking disparity of novel body plans appearing in the Cambrian explosion.
Related Concept Videos
Whole Body Regeneration
Diversity of Protists III
Neurulation
Cleavage and Blastulation
Gastrulation
Body Planes
The sagittal plane is the plane that divides the body or an organ vertically into right and left sides. If this vertical plane runs directly down the middle of the body resulting in equal division, it is called the midsagittal or median...

