A rounded urchin with short spines grazes the lagoon floor. Between those spines, small crabs and shrimps can find shelter.
- Local names
- Havae
- Habitat
- Lagoon and reef
About this species
Tripneustes gratilla varies in colour, with green, white, orange and reddish tones described in the guide. It feeds mainly on algae and seagrasses in lagoons, on algal reef flats and in seagrass beds. Zebra crabs and shrimps may associate with it.
It is most abundant in shallow water, especially the upper 15 m, though observations extend to roughly 75 m. The original guide’s local account emphasises depths of 1–10 m.
Small pincer-like organs called pedicellariae include venom-bearing structures. These are distinct from the short spines. Contact can be painful; leave the animal undisturbed rather than handling it.