Sea urchins are a group of marine invertebrates that have been around for a very long time.
Eucidaris metularia is a representative of the most primitive lineage, one that has survived with little change for the last 150 million years.
Species of Eucidaris are distinguished on colouring of their spines and test (plates) this species having characteristically strongly banded spines.
Eucidaris metularia © A Smith
Eucidaris metularia has a stout covering of spines used for protection and locomotion. Strong muscles at the base of the spines are protected by a palisade of small, flattened secondary spines.
The skeleton of plates (test) beneath the spines shows the characteristic pentaradial symmetry, common to all members of this group, especially clearly.
Tests are up to 30mm in diameter although usually smaller.
Find out more about the environment these sea urchins inhabit and where in the world they live.
Learn more about the biology and behaviour of the sea urchin Eucidaris metularia.
Eucidaris metularia
© A SmithEucidaris metularia
Eucidaris metularia
© A SmithEucidaris metularia
© A SmithTest
The series of plates that make up the sea urchin skeleton.