The Mediterranean Sea boasts an ancient geological history, and most marine organisms currently inhabiting it are of Atlantic origin, often referred to today as native Mediterranean species.

The Mediterranean is characterized by relatively high biodiversity, despite its area being less than 1% of the world’s oceans. It is home to 8,565 species, representing 6.5% of the total marine species worldwide. For instance, cartilaginous and bony fish account for 9.5% and 4.1%, respectively, of the known global species. Additionally, the Mediterranean hosts 18.4% of the world’s marine mammals, 8.6% of marine reptiles, 5.6% of marine invertebrates, and 16.9% of marine algae and plants. This richness is likely attributed to various historical and environmental factors, as well as influences related to ancient geography.