About Our Namesake
Although evidence is lacking, modern sea turtles probably descended from a single common ancestor during the Cretaceous period. Like all other sea turtles except the leatherback, loggerheads are members of the ancient family Cheloniidae, and appeared about 40 million years ago. Of the six species of living Cheloniidae, loggerheads are more closely related to the Kemp’s ridley sea turtle, olive ridley sea turtle, and the hawksbill turtle than they are to the atback turtle and the green turtle.
Around three million years ago, during the Pliocene epoch, Central America emerged from the sea, effectively cutting off currents between the Atlantic and Indo-Paci c Oceans. The rerouting of ocean currents led to climatic changes as the Earth entered a glacial cycle. Cold water upwelling around the Cape of Good Hope and reduction in water temperature at Cape Horn formed coldwater barriers to migrating turtles. The result was a complete isolation of the Atlantic and Paci c populations of loggerheads. During the most recent ice age, the beaches of southeastern North America were too cold for sea turtle eggs. As the Earth began to warm, loggerheads moved farther north, colonizing the northern beaches. Because of this, turtles nesting between North Carolina and northern Florida represent a different genetic population from those in southern Florida.
The distinct populations of loggerheads have unique characteristics and genetic differences. For example, Mediterranean loggerheads are smaller, on average, than Atlantic Ocean loggerheads. North Atlantic and Mediterranean loggerhead sea turtles are descendants of colonizing loggerheads from Tongaland, South Africa. South African loggerhead genes are still present in these populations today.
The Loggerhead sea turtle (Caretta) is the state reptile of South Carolina and the most common sea turtle nester along our shores. They are easily recognizable by the large size of their head in relation to their body and their brownish or yellow skin. Adults have top shells that measure from 30-42 inches in length and usually weigh up to 400 pounds. Males are larger than females, and are not known to come ashore once they leave their beach of birth. Females usually begin to nest the rst or second week in May; the nesting season usually ends by the end of August. Females usually emerge to nest at night and lay an average of 120 eggs per nest. They locate an appropriate nest site by judging the temperature and moisture of the sand. The female uses her rear ippers alternately to excavate a nest; when egg laying is completed, she covers the nest cavity, compacts the sand with the weight of her body and throws sand around with her front ippers. She then returns to the sea.