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Ocean Watch Susan Scott |
Reader spurs interest
in land turtlesOver the years, I've often written about sea turtles in this column, but I never mentioned freshwater, marsh or land turtles, because they aren't marine animals. But when one of my longtime readers e-mailed me that he found an ornate box turtle at Magic Island, and then asked several good questions about it, I thought it time to branch out.
His first question made me laugh: "Do you think your readers know the difference between a turtle and a tortoise?"
I found this amusing because I didn't know the difference myself. But I do now.
In Britain a species that lives strictly on land is a tortoise. The word "turtle" is used there only for aquatic types, either fresh, brackish or marine. Some of these aquatic types they call terrapins.
We Americans, of course, had to simplify things. We call all species turtles no matter where they live.
"How did the box turtle get its name?" my reader asks.
Box turtles are native to North American forests, where they forage for fruit and invertebrates. Three species of box turtles wander the woods, and all have one thing in common: The bottom shell is not fused into one solid piece. Rather, two hinges run the width, enabling the shell to flex.
When a box turtle is threatened, it pulls its head and legs inside the shell and flexes its hinges until the top and bottom shells meet. In this way, the turtle's soft, vulnerable parts are protected from predators. The stance also makes the turtle look boxlike.
Another question: "What's the difference between a freshwater turtle and a saltwater turtle?"
Saltwater turtles can't withdraw their head or legs inside their shells. They traded this ability, evolutionarily speaking, for broad, flat flippers that act as excellent swim fins. Also lost was the boxy body and domed top. Sea turtles bodies are streamlined for moving efficiently through water.
"Can turtles drown?" my reader asks.
Absolutely. All turtles are air breathers and can drown if held under the water too long. This is why unattended gill nets are so deadly. Sea turtles get caught in the nets and then can't get to the surface for a breath of air.
The new turtle owner also wonders, "Are turtles fast enough to catch fish?"
No. Sea turtles are good swimmers but are still no match for a fish. Mostly, sea turtles eat seaweed and jellyfish. If offered fish or squid, however, sea turtles accept them eagerly.
"I heard my box turtle moan when I covered it with a towel when I brought it home," my reader writes. "Is that normal?"
Turtles usually make noise only during mating season. Some sea turtles, however, make also sounds when injured.
"How large do box turtles grow?" he asks.
These small turtles rarely exceed 6 inches across.
And finally, "How can you tell a box turtle's age?"
I hope you like your turtle, Alvin, because one lived to be 138 years old. A farm boy found a box turtle with the numbers 1844 and initials E.B.K. carved into its shell. Investigation revealed that during that year, a young man named Edward Barber Kenyon lived on that same farm.
I had my own question about box turtles, which Alvin answered for me. "State agriculture said it's OK to have this species in Hawaii," he wrote.
Good. Now I want one, too.
Marine science writer Susan Scott can be reached at http://www.susanscott.net.