Water

A marine species, the Black Sea Turtle (Chelonia agassizii) depends on saltwater for many parts of its existence and spends most of its life in the water. When it comes to freshwater, sea turtles aren't like terrestrial tortoises; they won't drink from rivers or ponds. Rather, they've evolved a number of strategies specific to the saltwater environment that let them survive and even flourish there.

The existence of specialized salt glands is one of the main adaptations that allow black sea turtles to control their water demands in the ocean. Near their eyes, you'll find glands that may expel excess salt from their bodies. This is vital since the salt content of the water they drink when feeding is high. The salt glands keep their internal salt balance in check by secreting a concentrated brine that they release via their tear ducts, creating the illusion of "crying."

Black sea turtles get the water they need from the food they eat, but they won't drink freshwater either. They get a lot of water from the seagrass and algae they eat, which they digest and absorb. Their hydration requirements are met by this dietary water intake, which eliminates the need to directly consume freshwater.

Additionally, turtles' metabolic water synthesis aids with hydration. The biological reactions that transform food into energy produce metabolic water. The turtles' physiological requirements for hydration are met by this mechanism, which creates water as a byproduct.

Black sea turtles may have problems associated with dehydration when they are on land, which happens mostly when the females come ashore to lay their eggs. Nesting on a sandy beach and the physical effort required might cause water loss. Though their stays on land are brief, turtles have developed mechanisms to endure mild dehydration until they can go back to the water.

Black sea turtles also rely on water for temperature control. They are able to keep their core temperature in check with the aid of the ocean's steady thermal environment. Sea turtles, in contrast to terrestrial tortoises, are ectothermic, meaning they keep their body heat from the surrounding water. Thus, the metabolic activities and general health of these organisms are highly dependent on the temperature of the saltwater.