Heterocentrotus mamillatus

From Wikipedia, the free encyclopedia
  (Redirected from Red pencil urchin)
Jump to: navigation, search
For other species with the same common name, see Slate pencil urchin.
Red slate pencil urchin
Heterocentrotus mammillatus in situ from Hawaii.JPG
Scientific classification
Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea
Order: Echinoida
Family: Echinometridae
Genus: Heterocentrotus
Species: H. mamillatus
Binomial name
Heterocentrotus mamillatus
(Linnaeus, 1758)[1]

Heterocentrotus mamillatus, commonly known as the slate pencil urchin, red slate pencil urchin, or red pencil urchin, is a species of tropical sea urchin from the Indo-Pacific region.


Radiols (spikes) of a "slate pencil sea urchin". They are a classical souvenir.

This species is a big sea urchin, with a test reaching over 8cm and spikes up to 10cm. The classical color is bright red, but they can also be brown, or even purple. The test and spikes can be of different color, and the spikes can have a white ring at their stem, and be rounded with lighter or darker bands. The spikes are rouded to triangular in cross-section, but always blunt. Specimens from Hawai‘i tend to have bright red spines, while specimens from other parts of the Pacific may have yellowish or brown spines.

Heterocentrotus trigonarius is a similar species that has longer and darker spines, more angular, and is always monochromic.


This species can be found throughout the tropical waters of the Indo-Pacific region (from the African est coast to Pacific archipelagos), but is especially abundant in Hawai‘i. It is found in shallow waters, often close to surf reefs, between the surface and 8m, sometimes down to 25m.


  1. ^ Kroh, A. (2010). A. Kroh & R. Mooi, ed. "Heterocentrotus mamillatus (Linnaeus, 1758)". World Echinoidea Database. World Register of Marine Species.