The verdesca, or the blue shark, or the great blue shark, belongs to the class of Chondrichthyans, or cartilaginous fish. This shark can grow to 4 metres in length and weigh up to 200 kilograms. It lives mainly in the open sea, although it frequently approaches the coast. It often swims near the surface, but can also reach depths of 1000 metres. The verdesca has a dark back that gradually becomes lighter towards the sides, while the belly is white. This colour pattern is typical of open-sea fish and is called counter-shading. The verdesca is famous for its long migrations, which are studied using satellite tags. These tags send a signal to a satellite and therefore to the researchers every time the animal emerges to the surface. By applying these tags to several sharks, researchers discovered that the verdesca can cross the Atlantic Ocean. One female travelled 30,000 km in just over two and a half years. The verdesca feeds on cephalopod molluscs and fish, as well as marine birds. It is present in the Mediterranean, including the Adriatic Sea, and is caught by commercial and recreational fishermen. Fortunately, recreational fishermen today release all the verdesca they catch.