Also known as Purple Sea Urchin, Purple Spiny Sea Urchin.
Found singly or in groups often covered in debris, rubbish, seaweed and shell amongst rubble, sand and in seagrass meadows over coral and rocky reefs rich in red algae growth. The spines of this sea urchin are quite thick and blunt.
They feed on algae.
Length - 15cm
Depth - 2-130m
Widespread Eastern Atlantic, Mediterranean
This urchin has a habit of grabbing pieces of seaweed, shell or pebbles with its tube feet and covering itself. This may act as camouflage and protect it from predators and the sun.
Sea Urchins use tubed feet to get around, often in large impenetrable masses for protection.
Sometimes they hitch a lift on the back of crabs.
They have well developed jaws for grinding their prey.
Their anus is on top in most sea urchins, except the heart urchins where it is at the rear.
Predators of sea urchins are triggerfish and large wrasses, who nibble away at their spines before turning them over to eat the fleshy undersides.
Sea Urchins are highly venomous and can piece through a wet-suit.
Some are sensitive to light and have the ability to shoot venom loaded spines at a short distance.
To be avoided!! Ref: http://sealifebase.org/summary/Sphaerechinus-granularis.html