Movie 2

The alarm response of the sea urchin Diadema africanum, which occurs following exposure to a visual stimulus. The response consists of rapid spine-pointing of the sharp, venomous secondary spines following a sudden light decrement. No response occurs to light increment. The response occurs after a delay and localized to the sector of the animal surface which is exposed to the stimulus.

The sea urchin Diadema africanum uses low resolution vision to find shelter and deter enemies

John D. Kirwan, Michael J. Bok, Jochen Smolka, James J. Foster, José Carlos Hernández, and Dan-Eric Nilsson

Journal of Experimental Biology 2018. 221:None-None; doi: 10.1242/jeb.176271