The Mediterranean Sea covers an area of about 2.5 million km2 representing approximately 0.82% of the world ocean surface. It is bordered by 23 states and its coastline extends for around 45,500 km. With an average depth of 1,500 m, it reaches the deepest area at 5,267 m of the Ionian Sea. Today the Mediterranean Sea is known to host more than 17,000 marine species and contributes to an estimated 4-18% of the world’s marine biodiversity.
Mediterranean sea is a diverse place where corals live as solitary animals or in colonies, composed of rigid or soft structures; with those which prefer exposure to the sun or which live in zones of darkness. Although the number of coral species found in the Mediterranean represents less than 5% of those extant throughout the world today, they are capable of forming very complex and diverse communities.