The continuous release of CO2 in the atmosphere is increasing acidity seawater worldwide, and pH predicted to be reduced by ~0.4 units 2100. Ocean acidification (OA) changing carbonate chemistry, jeopardizing life marine organisms, particular calcifying organisms. Because their calcareous skeleton limited ability regulate acid–base balance, echinoids are among organisms most threatened OA. In t...

Although eyes are generally considered necessary for image resolution, a diffuse photoreceptive system with directional sensitivity may also have this ability. Two species of the echinoid genus Echinometra were tested for spatial vision by examining their ability to locate and move towards targets of different sizes. The echinoids were significantly oriented (P<0.0001) towards a target with an ...

Echinoids fauna are common and distributed in the Lower Miocene deposits of the Bagher Abad area, northeast Isfahan, Central Iran.There are six Echinoid taxa belonging to the Echinoidea Class that can be described as: Clypeaster intermedius, Prinocidaris sp. andspines related to: Eucidaris zaemays, Stylocidaris Polyacantha, Spatangoid sp. and Prinocidaris sp. Bivalves, Foraminifers,Bryozoans, B...