Sea Turtles

Sea Turtle History

The oldest fossils of turtles were found in Germany and date back 215 million years, during the Triassic period.1 They are among the oldest fossils of four-legged animals and one of the Earth’s most ancient creatures. These ancestral turtles had completely formed shells and lived on land, in marshes. Turtles appeared before dinosaurs and were present for the evolution of birds from feathered dinosaurs. It is not yet known when these turtles shifted into the ocean, becoming sea turtles, but over the eons, sea turtles have adapted very well to a marine environment:

  • Sea turtles breathe air, but can remain below the sea surface without air for over 45 minutes; when resting they can stay underwater for hours;
  • Sea turtles are excellent swimmers and divers. They developed hydrodynamic shells and paddle-shaped forelimbs that enable them to move easily and quickly in an aquatic environment;
  • Sea turtles rid themselves of excess seawater through tear glands; the salt water ingested with food is eliminated by the contractions of the esophagus to push out excess water whenever food is swallowed.

There are two groups of sea turtles: Dermochelyidae, including the Leatherback, are the most ancient sea turtles, the largest, and the only sea turtles without a hard shell; Cheloniidae, including the other six types of sea turtle, vary in size but all have a hard shell.


Photo: Dr. Michael Schmale

Rosenstiel School of Marine and Atmospheric Science campus

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