Tripneustes gratilla ( Linnaeus 1758 )

Yiu, Sam King Fung & Mah, Christopher L., 2024, New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong, Zootaxa 5526 (1), pp. 1-69 : 27-28

Tripneustes gratilla ( Linnaeus 1758)

FIGURE 17A–C

Comments

A commonly encountered species in shallow water Indo-Pacific settings. In Hong Kong, this species are observed in the Trio Island and the Ninepin Islands. Color varies, ranging from individuals with white to orange spines with dark or black test, especially along the interradial regions ( Fig. 17A–C ).

Tripneustes gratilla is herbivorous, feeding primarily on algae. Its feeding habits and ecology have been studied in populations across its range (e.g. Vaïtilingon et al. 2003), with particular relevance found in Hawaii where it has shown potential as a biological control agent ( Stimson et al. 2007).

Tripneustes gratilla is one of several urchin species that practices “covering behavior”, using tube feet to place rocks and other debris on its aboral surface ( Fig. 17A–C ). This species is best associated with this behavior, which is thought to be protective against ultraviolet radiation ( Ziegenhorn 2017).

Unlike other genera of wide-ranging urchin species, such as Echinometra mathaei ( McCartney et al. 2000) which have shown diversification specific to particular regions, phylogeographic studies of Tripneustes gratilla concluded that it is a large metapopulation spanning two oceans and containing chaotic, nonequilibrium local variation, produced by the haphazard arrival of larvae or by unpredictable local extinction (e.g. Lessios et al. 2003).

Occurrence/Distribution

Hong Kong, 3–10 m.

Outside Hong Kong, widely distributed across the East and Indo-Pacific Ocean, including the Galapagos and Clipperton Island, Hawaiian Islands, Southern Japan, Guam, Philippines, Marshall Islands, Australia, Indonesia, Papua New Guinea, to the Indian Ocean to South Africa, Madagascar, the eastern Africa coast and up to the northern Indian Ocean, 0–30 m (as per A.M. Clark & Liao 1995).

Figures

FIGURE 17. Tripneustes gratilla. Color morphotypes and in situ covering behavior. A. Dark orange morphotype. B. Yellow Morphotype. C. White morphotype. Photographer: Sam King Fung Yiu.