Echinothrix diadema
From Wikipedia, the free encyclopedia
-
- Several species of sea urchin are commonly called Diadema urchins, go here for a discussion
| iDiadema urchin | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 |
||||||||||||||||||
| Scientific classification | ||||||||||||||||||
|
||||||||||||||||||
|
|
||||||||||||||||||
| Echinothrix diadema Linnaeus, 1758 |
The Diadema Urchin (Echinothrix diadema) is a long spined urchin, with a diameter of about 8 cm. It is generally black in colour, and always dark. The spines are closed at the tip; the anal sac is spotted light and dark.
It is found in the Indo-Pacific region, in dark reef. It is active at night, hiding in crevices or under rocks at night.
It hosts commensal species like the shrimp Stegopontonia commensalis. Saron marmoratus stays close for protection, like many fish of the families Apogonidae (cardinal fish) and Aeoliscidae (razor fish).
The difference with Echinothrix calamaris is that spines are not banded. The more similar species is Diadema setosum, having longer spines, the distinguishing feature being the colour of the anal sac.
