Caspian Sea
The Caspian Sea, like the Black Sea, Namak Lake, and Lake Urmia, is a remnant of the ancient Paratethys Sea. It became landlocked about 5.5 million years ago due to tectonic uplift and a fall in sea level. During warm and dry climatic periods, the landlocked sea almost dried up, depositing evaporitic sediments like halite that were covered by wind-blown deposits and were sealed off as an evaporite sink when cool, wet climates refilled the basin. (Comparable evaporite beds underlie the Mediterranean.) Due to the current inflow of fresh water, the Caspian Sea is a freshwater lake in its northern portions, and is most saline on the Iranian shore, where the catchment basin contributes little flow. Currently, the mean salinity of the Caspian is one third that of Earth's oceans. The Garabogazköl embayment, which dried up when water flow from the main body of the Caspian was blocked in the 1980s but has since been restored, routinely exceeds oceanic salinity by a factor of 10.
Common octopus
The common octopus is typically found in tropical waters throughout the world, such as the Mediterranean Sea and East Atlantic. They prefer the floor of relatively shallow, rocky, coastal waters, often no deeper than 200 meters. Although they prefer around 36 grams per liter, salinity throughout their global habitat is found to be between roughly 30 and 45 grams of salt per liter of water. They are exposed to a wide variety of temperatures in their environments, however their preferred temperature ranges from about 15 °C to 16 °C. In especially warm seasons, the octopus can often be found deeper than usual in order to escape the warmer layers of water. In moving vertically throughout the water, the octopus is subjected to various pressures and temperatures which affect the concentration of oxygen available in the water. This can be understood through Henry's Law, which states that the concentration of a gas in a substance is proportional to pressure and solubility, which is influenced by temperature. These various discrepancies in oxygen availability introduce a requirement for regulation methods.