Sea turtles

Yet another endangered species. Did you know that

[t]he leatherback, the largest and oldest of the sea turtles, has been around 100 million years or so -- surviving the asteroid that 65 million years ago struck the Yucatan Peninsula, which scientists believe contributed to the extinction of the dinosaurs. Leatherbacks, though contemporaries of the dinosaurs, are reptiles and feed predominantly on another ancient creature: jellyfish.

The turtle gets its name from a leathery shell that has the texture of smooth, hard rubber. Its shell also has hydrodynamic dorsal ridges, which, combined with front flippers that can span 10 to 15 feet, enable these reptiles to soar like giant birds through the ocean.

Leatherbacks dive deeper than hard-shelled turtles -- nearly a mile -- because their supple shells can compress under the intense pressure. They also venture into colder waters because of an ability to regulate their body temperature.

Males spend their entire lives at sea, making them particularly difficult to study. The biggest male on record was 9 1/2 feet long and tipped the scales at nearly a ton. Females are smaller. Once they reach maturity, they venture ashore every three years, on average, to lay their eggs. That nesting routine provides researchers their only real opportunity to study these ancient animals.

But over-fishing, which traps the turtles in nets and on hooks, and poaching have led to a drop in the number of Pacific leatherback sea turtles, according to an article, "Sea Turtle Is Losing the Race" by Kenneth R. Weiss, in today's LA Times.