This study is a contribution in the knowledge of the common sea urchin Paracentrotus lividus (1816, Lamarck) using a combination of physical indices (IRm and IGm), studying his evolution during a year (November 2010 to October 2011), and analyzing the metal contamination in gonads. The sea urchin sampales was collected from two different biotopes: one is rocky and photophilous (La Salamandre), and the other with photophile algae and Posidonia (Sidi Lakhdar). A significant variation in time of IGm and MRI (P <0.005) with a large oviposition taking place in spring and autumn for all populations of sea urchins was observed, seawater and metal gonads contamination by cadmium (cd), iron (fe), copper (cu) , and zinc (zn) from both studied sites was determined by Spectrophotometry of Atomic Absorption with Flame. All the polluants sought are present with very heterogeneous concentrations; sea urchin accumulates relatively large quantities of toxic metals in proportion of their bioavailability in the surrounding environment.