Tripneustes gratilla (Cake urchin)


Variably colored, white, black, blue or even green. It has white and reddish/brown spines alternated by 10 spineless vertical bands (of pedicillaria). Tripneustes gratilla are often covered in debris.


Unassessed by the IUCN Red list, but it is one of the more common species of sea urchin in the Indo-Pacific.


Indo-Pacific; from the Red Sea and Eastern Africa to the Hawaiian islands. They prefer shallow bays, seagrass beds and lagoons with sand and debris, in a depth range of 0-75 meters.


Sexual reproduction. Fertilization is external and brooding is common. The eggs are held either on the peristome (the area around the mouth), around the periproct (anus) or deep into the concavities on the petaloids (skeletal plates). Sea urchin embryos develop into planktotrophic larvae (echinoplateus) and live for several months before they sink to the bottom. They use their tube feet to adhere on the ground where they metamorphose into young urchins.


Up to 10cm.

Prey / Predation

Tripneustes gratilla feed on algae and seagrass fronds. The urchins are preyed upon by puffer fish and octopus.

Special features

Also known by its other common names striped sea urchin and collector urchin