During one of the scuba diving we met the Pinna nobilis, common name the noble pen shell or fan mussel, is a large species of Mediterranean clam, a marine bivalve mollusc in the family Pinnidae, the pen shells. It reaches up to 100 cm of shell length. Pinna nobilis Noble pen shell intotheblue.it
The bivalve shell is usually 30–50 cm long, but can reach 100 cm. Its shape differs depending on the region it inhabits. It attaches itself to rocks using a strong byssus. These keratin fibres that the animal secretes by its byssus gland can be up to 6 cm long. The inside of the shell is lined with brilliant mother-of-pearl.
This species is endemic to the Mediterranean, where it lives offshore at depths ranging between 0.5 and 40 m. It could be found buried beneath soft-sediment areas. Pinna nobilis Noble pen shell intotheblue.it
Much of the Mediterranean coast enjoys a hot-summer Mediterranean climate. However, most of its southeastern coast has a hot desert climate, and much of Spain’s eastern (Mediterranean) coast has a cold semi-arid climate. Although they are rare, tropical cyclone occasionally form in the Mediterranean Sea, typically in September–November.
Because of the short residence time of waters, the Mediterranean Sea is considered a hot-spot for climate change effects. Deep water temperatures have increased by 0.12 °C (0.22 °F) between 1959 and 1989. According to climate projections, the Mediterranean Sea could become warmer. The decrease in precipitation over the region could lead to more evaporation ultimately increasing the Mediterranean Sea salinity. Because of the changes in temperature and salinity, the Mediterranean Sea may become more stratified by the end of the 21st century, with notable consequences on water circulation and biogeochemistry.