Down in the Jungleland: Call of the ocean

The remarkable life of sea turtles.

Written by Ranjit Lal | New Delhi | Updated: April 10, 2016 5:13:47 pm

Life is calling: Turtle hatchlings make a mad scramble towards the sea. Life is calling: Turtle hatchlings make a mad scramble towards the sea.

By all accounts, you wouldn’t want your mom to do to you what sea turtle moms do to their babies. In the dead of night, these heavyweight matrons lumber up on to a beach, beyond the high tide mark, dig clumsily with their flippers and in the depression they’ve made, drop a soft, round, glimmering white, very delicious to many, egg — one of as many as 150 others. Then they fling the sand over it again, flop down on the excavation site or labour off to the sea to frolic with potential Romeo turtles hanging around in the surf. Over the next several weeks, the egg will bake in the sun’s heat and its own metabolic process, and the prevailing temperature will determine whether what emerges is a girl or a boy: if it’s warm, it’ll be a little girl hatchling; if it’s cooler, a boy.

And oh, are the odds stacked against it! At best, the punters give it a 1:1000 chance of surviving to adulthood. It hatches, and spends maybe two days struggling to get out of its sandy cradle and clear the sand from its eyes. Hopefully, it’s dark when it does emerge and its miniscule brain will tell it to turn towards the brighter horizon: usually that’s where the sea and salvation and life lie as the moon and starlight are reflected off the waters.

If it’s not so lucky, it will find a welcoming committee of gulls, crows, jackals, cats, dogs, people et al waiting for it, malevolently licking their chops. With hundreds of siblings — and other baby turtles hatching all over the beach — it must now begin a mad helter-skelter scramble towards the light — but ah, sometimes even that can conceal the biggest betrayal of all. Bright lights spilling from human settlements, further inshore, can confuse it, and make it turn around and head inland instead. Mostly, it skedaddles towards the sea and with huge relief feels the surf wash over its sand-encrusted face as it begins swimming frantically headlong into the waves. And here, the second shift awaits it — predatory fish and seabirds who have been patiently waiting for just a moment like this. You know it must head straight into the approaching waves so as to get into the deep blue, but once it does, the waves begin to move directionlessly. So now where does it go?

Ah, never fear. As it dashes towards the brighter horizon, and then plunges into the waves, head-butting them, its tiny brain, senses and takes stock of a very important navigational aid: the earth’s magnetic field. Two readings are imprinted — the angle of inclination, and the magnetic intensity. Imagine the earth as a bar magnet, with magnetic lines streaming out from the south pole, going round and re-entering at the north pole. The angle of inclination would be the angle at which these lines intercept the earth’s surface at any location and would naturally vary with latitude. At the pole, the angle of inclination is 90 degrees, at the equator 0. Similarly, the intensity of the magnetic field will be maximum at the poles and minimum at the equator. These two readings, imprinted on its tiny brain, give it its bearings — and the rough latitudinal range it must keep to. It can sense subtle changes in the earth’s magnetic field in different parts of the ocean and use these as navigational markers as it roams the seas, eating aquatic insects, crustaceans, worms, jellyfish, sponges and carrion — and if vegetarian, aquatic plants. (As juveniles, they will be carnivores). Many decades later, after wandering the oceans (maybe 15,000 km or more), it will return to the waters where its parents met, make out with several partners, and if female, lumber up on to the same (or nearly same) beach where it was born, to lay its eggs. Some say, it actually does recognise the taste of the water near its birthplace and follow that like a scent — the smell of home!

Certainly, sea turtles live remarkable lives. Sad-eyed and somewhat goofy looking, they drink salt water (the salt is filtered out through their tears), may live for more than a hundred years, may never set foot on dry land after that first mad dash (females only come out to lay eggs). Their mass arrival on the beaches and the mouths of rivers is called the arribada. Five species are found in our offshore waters — the Hawksbill, Loggerhead, Green, Olive Ridley and Leatherback. As a group, turtles, tortoises (the landlubbers) and terrapins (which are small freshwater turtles) go back even further than crocodiles and snakes, some 157 million years. Hefty leatherbacks can grow to 6.5 feet and tip the scales at nearly a ton. They live a very long time and it’s been found that the vital organs — kidneys, lungs and liver — of some of them do not age, which has excited scientists no end.

As always, our treatment of them has been abominable. Many species, including all the Asian ones, are endangered, some are on the brink of extinction. We use them for food, for their shells, for the pet trade — and the Chinese as “medicines”. Many drown in fishing nets.

Fortunately, they have their friends and fans too. There’s the International Sea Turtle Society and of course, scores of ordinary people around the world who monitor their fate and trends and who will do anything to ensure that the game little bugger making that frantic dash to the sea gets there safely.

Ranjit Lal is an author, environmentalist and bird watcher.

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