Appearance
The Banded sea urchin has a slightly oval test , reaching a diameter of about 5 cm.Like almost all the Diadematidae it has two different sets of spines, shorter and slender closed spines which are going from yellow to dark in colour and can deliver a nasty sting, and longer and thicker spines that are often banded with light and dark colour , and reaching 10 to 15 cm in length.
These radiolas can be blunt, and are hollow. The spines are grouped so as to let appear five naked zones on the central part of the test, in a star pattern : this pattern can be colored, often in blue.
The anal papilla is big, more or less translucent and very obvious on the aborale face; it is generally whitish and speckled with black and white dots, circled by a ring of visual receptors that grant it a rudimentary vision.
In his darkest forms, it can be confused with its cousins ''Diadema setosum'' or ''Diadema savignyi'' ; however the latter is bigger, more uniformly black, has less discernible secondary radioles and is recognizable in five characteristic white points at the top of its test as well as in orange-colored circle around its anus.
The most common confusion is with the very close species ''Echinothrix diadema'', which can have banded spines when yound. But ''E. diadema'' has a very small anal papilla, all black, and the spines have a blue sheen ; the primary radiolas of ''E. calamaris'' are more fragile too, and can be crushed between two fingers , what is not the case for ''E. diadema''.
Distribution
The Banded sea urchin is widespread throughout the tropical waters of the Indo-Pacific region, from eastern coast of Africa to French Polynesia, including Hawaii and the Red Sea.It occurs from the surface to 70 metres depth and can be found in lagoons, external reef slopes and channels.
Behavior
This sea urchin is active at night, hiding in crevices or under rocks during the day.
Habitat
The Banded sea urchin is widespread throughout the tropical waters of the Indo-Pacific region, from eastern coast of Africa to French Polynesia, including Hawaii and the Red Sea.It occurs from the surface to 70 metres depth and can be found in lagoons, external reef slopes and channels.
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