sea urchin Diadema setosum

Identity card

sea urchin

Scientific name:
Diadema setosum
Year of description:
Leske, 1778
IUCN Status:
Not Evaluated

Not Evaluated


Red Sea, Indian Ocean, Pacific Ocean as far as Polynesia and from southern Japan to Australia


It lives at shallow depths in lagoons.


It measures about 10 cm including its legs and has a shell measuring 3 cm. It looks similar to a spider.


Encrusting algae and organic matter.

sea urchin Diadema setosum

To defend themselves against predators, such as titan triggerfish, sea urchins form large groups.


The sea urchin provides shelter for many animals such as gobies, cardinalfish, shrimps and even some jellyfish. The Banggai cardinalfish also hides in its spines to protect itself from potential predators.

did you know?

Biomimicry: the sea urchin's mouth and teeth have been used as a model for a grabber capable of sampling sediments on other planets such as Mars.

Where is the animal to be found?

It is found in the Red Sea, the Indian Ocean, Reunion and Mayotte, Madagascar, the Mascarene Basin, the Pacific Ocean as far as Polynesia and from southern Japan to Australia and New Caledonia. It is now found in the eastern Mediterranean, probably as a result of its larva being transported through the Suez Canal.

It lives in lagoons, on the surface of rocks, and on the sand near coral reefs, usually at a shallow depths. It is also found in seagrass beds and in disrupted environments where dead corals are abundant.

How can it be recognised?

Males and females cannot be identified morphologically. It looks similar to a spider.

What is distinctive about it?

Sea urchins breed by external reproduction, usually when the water temperature exceeds 24°C. The larvae drift for several months before sinking to the seabed to metamorphose into young urchins.

sea urchin  Diadema setosum

Where can I find it at Nausicaá?

mankind and shores

The Coral jungle

The Ocean Mag

Browse through our Ocean Mag

A la une

A treaty on biodiversity in the high seas

More than 80 states gathered at the United Nations in New York have already signed the international treaty on the protection of the high seas.

banc de mérous ile de malpelo


A brief glossary of terms covering the poles and glaciers

Do you speak polar? What is the difference between pack ice and icebergs? Here are a few definitions to help you understand the cryosphere.


Poles, glaciers and climate change

A look at why glaciers and the poles are important in the fight against climate change.