Banded sea urchin, Double spined urchin
Echinothrix calamaris, known commonly as the banded sea urchin or double spined urchin among other vernacular names, is a species of sea urchin in the family Diadematidae.
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OmnivoreAn omnivore is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and ani...
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CrawlingOv
OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
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starts withThe banded sea urchin has a slightly oval test (shell), reaching a diameter of about 5 cm.Like almost all the Diadematidae (but it is in Echinothrix calamaris that it is most obvious) it has two different sets of spines, short and slender closed spines which go from yellow to dark (through brown) in colour and can deliver a nasty sting, and longer and thicker spines that are often banded with light and dark colour (but sometimes all dark or all white), 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 (called "iridophores"): 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 rudimentary vision.
In its darkest forms, it can be confused with its cousins Diadema setosum or Diadema savignyi (which can both keep banded radiola when adult) ; 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 young. 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 (they are hollow), what is not the case for E. diadema.
The banded sea urchin is widespread throughout the tropical waters of the Indo-Pacific region, from the eastern coast of Africa to French Polynesia, including Hawaii and the Red Sea.
It occurs from the surface to 70 metres (230 ft) depth and can be found in lagoons, external reef slopes and channels.
This sea urchin is active at night, hiding in crevices or under rocks during the day.
The thinner spines are venomous (but not dangerous).
