Sea Urchins
CLASS ECHINOIDEA
SPECIES OF Sea Urchins
CLICK ON A CATEGORY BELOW TO FIND OUT MORE!
ANATOMY OF Sea Urchins
OVERVIEW
Sea urchins are super spiky, while their sand dollar cousins are less so! Both groups belong to the same class Echinoidea, which means “spiny” in Greek.
SEA HEDGEHOGS AND DOLLAR COINS!
Sea urchins are spherical or oval-shaped animals that are full of long and scary-looking spines. In fact, the word “urchin” is actually derived from the Latin word for “hedgehog”! In contrast, sand dollars are flat, round and look like coins. Their spines are much shorter and softer than the long and sharp spines of their sea urchin cousins.
TEST OF RESILIENCE!
Sometimes, our shores are littered with round, hollow, ball-like objects. These are not shells! They are actually the skeletons of sea urchins, also known as their test! When sea urchins die, their bodies decompose and all their spines drop off, leaving a naked and empty test behind.
MULTI-FUNCTIONAL SPINES!
An armour of strong and tough spines is probably one of the best defences an animal can have! But besides protecting themselves against predators, some sea urchins also use their spines as feet to move around, or as spades for burrowing into the sand.