Oursin diadème - Aquarium La Rochelle

Hatpin Urchin

Diadema setosum
Conservation status :

Not evaluated

  • Group
  • Size
    9 centimetres in diameter
  • Distribution area

    This urchin lives in the lagoons of the Indo-Pacific region, from the east coast of Africa to Japan and New Caledonia. It can also be found in the Red Sea.

this character

The hatpin urchin prefers sandy beds at the base of coral colonies, between 0 and 25 m below the surface.

This gregarious creature that feeds on algae is often found in groups, particularly during the day.


The urchin can be recognized by its long spines (up to 15 cm) and the orange-red ring around its anus on its posterior. Hatpin urchins are usually black, but their spines can also be lighter in colour (grey, white or purple) or even striped in juveniles.


Like all sea urchins, these spines are mobile, allowing the animal to point them toward any danger that may be threatening it. It is sometimes used as a refuge by shrimp and small fish.


The hatpin urchin's long, thin spines are covered with tiny barbs. These are not venomous but can easily slip into the skin, breaking off and becoming embedded only to later cause infection.

« The hatpin urchin can now be found in the Eastern Mediterranean. This extension of its range is undoubtedly due to the movement of its larvae through the Suez Canal. »

The artist on stage

Find us also on

Join our fans on

follow the news of the aquarium continuously on

Find us also on