Sea turtles are ancient, but not primitive. Having evolved on land some 200 million years ago, they spend their entire lives at sea except to lay eggs on rugged beaches around the globe.

Leatherback turtles are the largest of the seven seafaring species and they are truly remarkable, most worthy of admiration and in need of protection.

Leatherbacks are Earth's last warm-blooded reptiles and their weight can easily exceed one ton.

All sea turtles except leatherbacks have shells. Leatherbacks instead have backs with a jigsaw of thousands of small, thin bones overlaid by a thick matrix of oily fat and fibrous tissue. Their belly has only a narrow oval bone with heavy fibrous tissues.

They are the fastest-growing reptiles in nature -- and the fastest-swimming turtle with the widest distribution. Their four legs are wings in the sea and shovels on the beach.

Leatherbacks live in both the Atlantic and Pacific Oceans.

Atlantic leatherbacks nest every other year, with clutches of about 85 eggs. Pacific leatherbacks, on the other hand, nest every fourth year and only produce clutch sizes of approximately 65 eggs.

After the female digs the nest, she fills the chamber with eggs, but the first couple dozen are yokeless. It is thought that these first eggs provide air spaces at the top of the nest, stabilize humidity, protect against fungus and insects and, after two months of incubation, provide "elbow room" for the unusually long-winged hatchlings.

Just like the dinosaurs, the sex of the sea turtle eggs are determined by nesting temperature. That is, if the eggs are slightly warmer, the offspring will be female; conversely cooler temperatures yield males.

A hatchling will grow to 30 times its size and add 6,000-fold in weight. They probably mature by the age of 12 and live in the wild for almost 60 years.

Leatherbacks born in Trinidad, St. Croix, Costa Rica, French Guiana, Florida and South Carolina travel north to the icy waters of Cape Breton. They have adapted to these frigid conditions with bones that are tipped with cartilage packed with blood vessels rich in nutrients -- a trait common in mammals.

Leatherbacks gorge themselves on giant stinging lion's mane and moon jellyfish (some in excess of two metres wide). Extremely long esophagi enable each leatherback to consume about three dozen jellies a day.

This region of the North Atlantic is the richest feeding ground for leatherbacks on Earth.

From Cape Breton, they journey thousands of kilometres to the shores of Spain or North Africa before returning to breed in the southeastern Atlantic.

Leatherbacks are also the deepest deep-sea divers on the globe. Their incredible high red blood-cell density allows them to out-dive even sperm whales as they forage 1.2 kilometres beneath the surface.

Leatherbacks -- like other sea turtles and sea birds -- have glands near their eyes that filter and discharge salt, enabling these animals to drink full-strength salt water without dehydration.

Populations of leatherbacks in the Pacific travel an astounding 11,000 kilometres from the shores of Japan (and a small fraction from Australia) to Baja, Mexico, or from New Guinea to western Costa Rica. Populations appear to stay for a couple decades off their migratory shores before swimming across the Pacific to breed.

Leatherbacks have the widest distribution of any animal in the world except some of the great whales.

The only natural predator of leatherbacks was T. rex, but they became extinct about 65 million years ago.

At the dawn of the 20th century, there were very likely billions of sea turtles. Over the past 100 years, at least 90 per cent of sea turtles have vanished.

Each year, about 1.4 billion hooks from commercial fisheries are set into the oceans. Longlines are fishing lines up to 100 kilometres long, dangling hundreds or more likely thousands of baited hooks, and as many as 10 leatherbacks have been caught by a single line.

Egg poachers have also annihilated leatherback populations. There are about 35,000 female leatherbacks remaining on the planet.

In the Atlantic, conservation biologists and indigenous peoples are working together to save the leatherbacks and some of the populations are beginning to respond. For instance, from 1980 to 2000, the St. Croix leatherbacks have rebounded from 20 to 200 -- a tenfold increase.

Pacific populations, however, are in dire jeopardy, especially from egg poachers. Senseless poaching in the 21st century is unacceptable. If allowed to breed, leatherback populations will slowly rebound.

They have survived on our planet for more than 100 million years. Their extinction must be prevented.