Also known as Collector Urchin, Pincushion Urchin, Spotted Urchin, Stained Collector Urchin, Tinged Sea Urchin.
Found singly or in groups over coral and rocky substrates of coral and rocky reefs. Often covered in algae and debris.
They feed on coralline algae.
Length - 11cm
Depth - 0-80m
Widespread Western Pacific
Cake urchins have a blue, purple to brown body, short white spines sometimes tipped with orange, and brownish-red tube feet. In some years it can be abundant while in other years quite rare.
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://www.saltcorner.com/AquariumLibrary/browsespecies.php?CritterID=3140