Eucidaris thouarsii

Eucidaris thouarsii, the slate pencil urchin (named after slate pencil), is a species of cidaroid sea urchins that inhabits littoral regions of the East Pacific Ocean.^[1][2]

Eucidaris thouarsii
Eucidaris thouarsii in the Gulf of California
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Echinoidea
Order:	Cidaroida
Family:	Cidaridae
Genus:	Eucidaris
Species:	E. thouarsii
Binomial name
Eucidaris thouarsii (Agassiz & Desor, 1846)

Distribution and habitat

Eucidaris (thouarsii) galapagensis of the Galápagos, Clipperton and Cocos Islands was formerly included as a subspecies, but is now generally recognized as a separate species

Eucidaris thouarsii is found in the East Pacific at depths of 0–45 m (0–148 ft), ranging from Baja California to Panama, as well as Cocos Island, Clipperton Island and the Galápagos Islands.^[3][4][5] The Galápagos, Clipperton and Cocos populations are now often recognized as a separate species, E. galapagensis, instead of a subspecies of E. thouarsii.^[6]

Diet

Like all urchins these are primarily herbivores, but feed on a wide range of invertebrates.^[7] This species has a high nutrient absorption efficiency when it comes to the coral Pocillopora damicornis, but would require a large intake to make nutrient requirements.^[8] Due to its high intake of coral, it reduces reef growth.^[9]