When an animal dies, its body changes in appearance. It will gradually disappear as it is eaten by other animals and bacteria. This process is called decomposition. When a sea turtle dies, the first thing that happens is that the body of the turtle, known as a carcass, sinks to the bottom of the sea floor. However, the bacteria in its intestines continue to live and produce gases, gradually making the body swell. Like a balloon filled with air, the body floats and rises to the sea surface. But, as the bacteria continue to decompose the body, the carcass will eventually develop holes and let out the gases that kept it on the surface. It sinks again and disappears to the bottom of the sea permanently.
The turtles found stranded on Virginia's beaches arrived floating. They had not yet released the gases they contained, otherwise they would have sunk and remained at the bottom of the sea without reaching the beach. Since we ultimately wanted to understand why these sea turtles died, we first needed to figure out where and when they died.

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