Sea urchin is a ball-shaped echinoderm living on sea beds, usually near coral reefs. It has long and pointy spines all over its body. The spines help in locomotion. Certain species have spikes filled with venom.
The majority of them are black, brown, purple, red or green in colour. Their colour depends on the species.
It has a special type of mouth, called Aristotle’s lantern, which is equipped with five sharp teeth that are able to drill a hole in the rock.
It feeds on sea weed, algae, plankton and decaying organic matter.
Unlike humans they don’t rely on a bone structure to support their bodies.
Urchins have a shell-like structure which is called a “test”.
The hard shell made from calcium carbonate is similar to that of starfish and sand dollars and is their main form of protection.
The structure consists of small plate segments that enclose the urchin; it looks a bit like the segments of an orange.
As well as the “test” they have spines which help them protect themselves from predators.
Picture Credit : Google
