This sea urchin was first described in 1867 by the American zoologist Addison Emery Verrill who gave it the name Psammechinus pictus.

[5] These sea urchins tend to form dense aggregations at the edge of, or inside, the kelp beds that line this coast.

During the day it may semi-bury itself in sand, and it sometimes disguises itself with fragments of shell and gravel held in place by its tube feet.

[5] It feeds on kelp, particularly Macrocystis, Gigartina and Laminaria, but primarily grazes on young stages rather than fully-grown fronds.

In the California kelp forests, the painted urchin is preyed on by the bat star (Patiria miniata).