The leatherback turtles are true giants. They are the largest of all marine turtles and the heaviest reptiles in the world. Their very distinctive shells have a leathery appearance and are often close to 8 feet long and weighing up to 2000 pounds. It is thought that the leatherback's bulk enables it to maintain its body temperature that allows it to swim into more temperate waters than any other turtle. Leatherbacks are apparently unaffected by sea temperatures even below 5 degrees C (41F) and they range as far north as the seas around Alaska. They are also found in the oceans off the Chilean coast as well as close to New Zealand. There is some concern that global warming may be affecting the range of these turtles because every once in awhile a turtle is found stranded on a beach far from the tropics.
Leatherbacks return to the tropics to breed. The females return to the beach where they were born to lay their own eggs. It is thought that the female leatherback, after she has completed the task of egg laying, circles the nest site, just as the young do once they hatch. It may be that this behaviour somehow imprints onto the memories of the youngersters , aiding their return to the same place. They try to find remote beaches which they can haul themselves up onto without difficulty and where they can come directly out of the deep seas rather than swimming over reefs. Although they lay eggs on their own, they sometimes nest in small groups especially where there is an ideal beach. The females come ashore every two to three years and typically lay 6-9 clutches per season. Each of the clutches consist of about 80 viable eggs; however only about one of those turtles lives to the age of 20. Even though the turtles are programmed to dig themselves out at night there are still lots of predators around to snatch them up before they reach the sea. Of course once in the sea a 2.5 inch turtle makes a nice snack for just about anything? Even once they are full grown they face a number of predatore such as various sharks and killer whales.
In addition they face continued problems being caught in fishing nets and swallowing plastic bags and other refuse that looks like their almost exclusive food jelly fish. Fishermen are being educated to use devices to keep turtles out of their nets but there is still a long way to go. Leatherbacks are on the critically endangered list and considering that they have been around for 150 million years it would be a travesty if such an incredible creature became extinct.
After almost a two hour bus ride up to Levera Beach we were met by Leticia, our guide for the evening. She gave us an overview of the program and the dos and don'ts of turtle watching. The researchers and scientific team are working hard to maintain the numbers of leatherbacks that visit Grenada to lay their eggs and are out on the beaches each and every night during the season. Part of the cost of our tour to Levera was a donation to help the researchers continue in their efforts to save these amazing reptiles.
From the station we were taken out to the beach to wait. The most recent group had had to wait until 11pm before a turtle came ashore. No sooner had we walked onto the sandy full moon lit beach than we saw the shadows of something large along the shore. We had to keep our distance initially but we watched in awe as this 1500 pound creature crawled up and over a berm of sand. It was obviously a supreme effort for her. When she was content with her nest spot she began to use her rear flippers alternately to dig a hole. She digs until her flipper can no longer reach the bottom of the hole. Once she was digging we were allowed to stand behind her. Only red lights are used as turtles can not see colours. Fortunately we also had a full moon which allowed us even better viewing.
Once her hole is dug the researchers place a rope in the clutch so that they can find the eggs again. Often they have to move them further up the beach if they are in danger of being undermined by the sea. When she is laying she goes into a kind of trance and is less aware of what is going on around her. They lay about 80 large viable eggs and another 40 or so small eggs that provide hydration for the hatchlings.
After she was done and still calm we were given an opportunity to touch her shell as well as her flippers. The shell is quite leathery and can stand the pressure in deep water. By compressing it allows them to dive to extreme depths of upwards of five thousand feet in search of jelly fish. We thought the flippers would be hard but they felt like sponges.
After she finished laying she used her back flippers to fill in the hole and her front flippers to begin camouflaging the area. This process took a good hour and a great deal of effort on her part. You could hear her puffing at times and before she was through the area looked like a small bobcat had been working in the sand.
And true to the information that I read she did in fact go in a circle. Once she was finished it was time to move back and let her focus on returning to the ocean. It was a very moving sight watching this huge creature return to the sea. All in all the whole process had taken about two and a half hours. Before we left the beach two more turtles had climbed out on to the beach and the second research team around in the next bay reported that they had five turtles.
What a once in a lift time experience it had been! We felt very honoured and humbled to have been given the opportunity to witness one of nature's amazing spectacles. Let us hope that these amazing turtles are around for another 150 million years.
