The Persistence of Turtles

White-lipped Mud Turtle (Kinosternon leucostomum) at Finca Cantaros in a fruit orchard. Found in Pacific drainages from Costa Rica to Ecuador; Caribbean drainages from Mexico to northern Colombia. Lays 1-4 eggs on the ground under leaf litter.

White-lipped Mud Turtle (Kinosternon leucostomum) at Finca Cantaros in a fruit orchard. Found in Pacific slopes from Costa Rica to Ecuador; Caribbean slopes from Mexico to northern Colombia. Females lay 1-4 eggs on the ground under leaf litter between July and October.

 

Turtles may be one of the first animals to capture a child’s imagination. To see the final drawing of Aesop’s winning tale of The Tortoise and the Hare, and to learn that “slow and steady wins the race” is to empower a child to keep trying and never, ever, give up. For adults, the fable’s lesson has been retooled by corporate motivators to inspire hard work and profit-making. Turtles have colonized most biomes on earth except Antarctica, so people everywhere are exposed to them and seem to develop affection for them precisely because, unlike other reptiles that can move or strike in the blink of an eye, most turtles are tranquil and non-aggressive. They can be trusted. My mother, not exactly an intrepid outdoorswoman, nonetheless felt protective of turtles, stopping to pick up small cooters, box or pond turtles on busy roads in our Massachusetts neighborhood to remove them from harm’s way.

The plastron (underside) of the White-lipped Mud Turtle has a hinge, and the animal can completely withdraw into its shell, sealing the opening by closing the plastron against the carapace.

The plastron (underside) of the White-lipped Mud Turtle has a hinge, and the animal can completely withdraw into its shell, sealing the opening by closing the plastron against the carapace.

Turtles persist. They age, but hardly grow old! Their organs don’t deteriorate with time as mammals’ do. Herpetologists at the American Museum of Natural History have learned that the liver, lungs and kidneys of a 100-year old turtle are almost indistinguishable from those of a juvenile counterpart, inspiring research of the turtle genome for novel longevity genes. Some Seychelles and Galapagos tortoises have lived to 175 years before dying of old age—perhaps as many as 250 years, as claimed for Adwaita, a giant tortoise that died in a Calcutta zoo in 2006.

And at the Smithsonian Institution, herpetologists found turtles’ hearts are not stimulated by nerves, and don’t need to beat constantly. Having the power to turn off their ticker at will may account in part for their longevity. The herpetologists’ research also found that among some populations of sea turtles, females don’t reach sexual maturity until they reach 40 or 50 years of age, and that could be “a record in the animal kingdom.” Then they continue producing eggs until they die.

Common Snapping Turtle (Chelydra serpentine) at Finca Cantaros, sunning on a log at the edge of Laguna Zoncho. The female lays up to 80 eggs.

Common Snapping Turtle (Chelydra serpentine) at Finca Cantaros, sunning on a log at the edge of Laguna Zoncho. The female lays up to 80 eggs.

At Finca Cantaros, with its year-round pond and rainy season marsh conditions, turtles seem to thrive. We find them as half buried eggs, sunning on logs, lumbering along on forest trails, swimming with their noses aloft in the pond, and even roaming grassy fields under fruit trees. The main predators here, especially of turtle eggs, must be animals such as the rather common opossum (“zorro”), armadillo, tayra, a weasel-like animal (“tolomuco”), and the odd otter (“nutria”). In turn, turtles are omnivorous, consuming plants, fruits, insects, mollusks, frogs, and fish.

Red-footed Tortoise (Chelonoidis carbonaria in a road in the Pantanal region of Brazil. Vulnerable to extinction due to over-collection for food and the pet trade. Main threats are jaguars and humans. Can reach 16 inches. Tortoises have completely terrestrial habits.

Red-footed Tortoise (Chelonoidis carbonaria) removed from danger on a dirt road in the Pantanal region of Brazil. Vulnerable to extinction due to over-collection for food and the pet trade, its main threats are jaguars and humans.It can reach 16 inches in length. Tortoises have completely terrestrial habits and this tortoise lives about fifty years.

Reminding me of the divine freedom I enjoyed as a young New Englander to wander woods and meadows and explore brooks, marshes and ponds, every time I find a turtle even now I feel pure exuberance. As a child I tried to imagine what it would be like to be them: swimming so encumbered; chomping on watercress, minnows and crayfish; hiding in dappled waters. Perhaps it is their benign nature that appeals, their unique architecture, and their impenetrable eyes glinting from ancient lineages going back 230 million years or more. From childhood wading, when I just wanted to catch and hold a turtle to study its shell and wait for its head to emerge from the carapace, I have since been convinced that turtles deserve not just wonder and respect, but active protection. About half of the world’s only 250 species of turtles today are considered endangered or threatened.

Red-footed Tortoises may aestivate (go into a dormant or torpid condition) in dry weather for several months. The scales on their shells are called skutes.

Red-footed Tortoises may aestivate (go into a dormant or torpid condition) in dry weather for several months. The scales on their shells are called skutes.

When I think of the “progress” that co-opted some of the beautiful turtle and frog territories I explored as a child and teenager, multiplied everywhere and unceasingly worldwide, my inherent optimism tends toward despair. Turtles have been hardy and critical survivors, contributors to the health of diverse fresh and salt water ecosystems, even deserts, but they are poorly equipped to deal with the myriad and expanding human threats from habitat loss to climate change. Threats to sea turtles seem particularly acute.

Evolutionary biologists seem to agree that somewhere in our distant past we humans share an ancestor with turtles. We can thank that ancestor for what some neuroscientists call our reptilian brain, the primitive, instinctive part of the brain that governs the functions over which we have no or little conscious control, like balance, breathing, heart rate, and body temperature. We must hope that the human brain’s more complex limbic system and neocortex, which contribute to making us the rational, caring and creative innovators we are capable of being, will soon, with farsighted leadership, enable earthlings to properly prioritize and insist on sustainability for all precious life.

A recently hatched unidentified turtle found at the highest point of the Finca Cantaros property. Turtles are on their own from the moment the egg is laid. They remain solitary throughout their lives except at mating time when males must actively court females in order to be selected.

A recently hatched unidentified turtle (2 inches) found at the highest point of the Finca Cantaros property. Turtles are on their own from the moment the egg is laid. They remain solitary throughout their lives except at mating time when males must actively court females in order to be selected.

 

Sometimes I feel that I live in a bubble in Costa Rica, surrounded by lush vegetation in my seven hectares, in a country that protects a larger percentage of its natural resources than any other. I have created a nature reserve, and am “acting locally” in what I think is a responsible way. But how do I quash the guilty sense that I should be doing so much more to help turtles and other creatures everywhere?

 

 

 

 

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References:

Slow is Beautiful, by Natalie Angier, in Science Times, New York Times, December 12, 2006. Many of the facts in my post were selected from Ms. Angier’s comprehensive article, highly recommended for those interested in turtle biology and conservation.Emerson quote

A Guide to Amphibians and Reptiles of Costa Rica, by Twan Leenders. A Zona Tropical Publication, 2001

Amphibians and Reptiles of La Selva, Costa Rica, and the Caribbean Slope–A Comprehensive Guide by Craig Guyer and Maureen A. Donnelly. University of California Press, 2005.

The Natural History of Intellect by Ralph Waldo Emerson, 1893: (From Bartlett’s Quotations.)

Recommendation:

Self-Portrait with Turtles, A Memoir by David M. Carroll, Houghton Mifflin Company, 2004.

I loved this book. David Carroll is a New Hampshire illustrator, author, naturalist and conservationist whose life’s work has centered on turtles and the natural systems in which they live. He was selected as a MacArthur Foundation Fellow in 2006.

 

 

 

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