Echinocyamus pusillus (O F Müller, 1776)

Echinocyamus pusillus

Description: A tiny oval, flattened sea urchin which lives in coarse gravel. When alive its colour is grey-green but on being hurt or damaged it turns bright green. The spines are short and give the animal a velvet texture. The anus is on the underside of the test posterior to the central mouth. Typically only 1cm. in length.

Habitat: Lives buried in coarse gravel where it feeds on detritus and Foraminifera. Difficult to collect owing to its small size.

Distribution: Recorded from all round the British Isles.

Similar Species: Unique, the only member of the order Clypeasteroida in the British Isles.

Key Identification Features:

• Tiny oval sea urchin.
• Turns green if damaged or preserved.
• Anus on underside of test.

Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.

WoRMS: Species record : World Register of Marine Species.

iNaturalist: Species account : iNaturalist World Species Observations database