Loggerhead turtles are the most abundant of all the marine turtle species in U.S. waters. But persistent population declines due to pollution, shrimp trawling, and development in their nesting areas, among other factors, have kept this wide-ranging sea-goer on the threatened species list since 1978. Their enormous range encompasses all but the most frigid waters of the world's oceans. They seem to prefer coastal habitats, but often frequent inland water bodies and will travel hundreds of miles out to sea. The largest of all hard-shelled turtles’ leatherbacks are bigger but have soft shells loggerheads have massive heads, strong jaws, and a reddish-brown shell, or carapace. Adult males reach about three feet in shell length and weigh about 250 pounds, but large specimens of more than 1,000 pounds have been found. They are primarily carnivores, munching jellyfish, conchs, crabs, and even fish, but will eat seaweed and sargassum occasionally. Mature females will often return, sometimes over thousands of miles, to the beach where they hatched to lay their eggs. Worldwide population numbers are unknown, but scientists studying nesting populations are seeing marked decreases despite endangered species protections.