Some turtles, tortoises still endangered despite hard shell
In a program with the DuPage Forest Preserve and Illinois Department of Natural Resources, Brookfield Zoo is nurturing endangered Blanding’s turtles so they can boost populations in the wild.
Courtesy of Jim Schulz, Chicago Zoological Society
You wanted to know
« Why is the belly of the tortoise not as hard as the shell? » asked a young Vernon Area Library patron inspired by a library program featuring the Flying Fox Conservation Fund.
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Andy Snider, Brookfield Zoo curator of herpetology and aquatics, said it all depends on where you live.
« All tortoises are turtles, but not all turtles are tortoises, » he said.
All tortoises and turtles come from the order chelonii, or testudines. In the U.S., the land-based, chunky-footed, lumbering green reptiles are tortoises. You might often see green discs sunning on a log projected out over a pond — those are turtles and they spend much of their time paddling around the water.
In winter, these round reptiles hibernate in the mud, which protects them from freezing temperatures.
Terrapins, another sort of turtle, live in river water. Sea turtles, well, you know where they live. People in other countries use tortoise to refer to nearly all these hard-shell reptiles.
« They’re not soft on the bottom, » Snider said of tortoise and turtle tummies. He explained that the carapace, the hard top shell, and the plastron, the part of the shell that covers a turtle’s underside, are actually one hard bone-like piece connected by a bridge.
« It’s a part of the tortoise just like our skin is a part of our bodies. »
Turtles have remained unchanged by evolution since they first arrived 200 million years ago, branching from an ancestor that was 10 feet long from head to tail with flipper-like legs used to navigate the watery environment. The protective home that surrounds these reptiles has proved to be a great design, so well made that tortoises can live more than 80 years. Rings on the carapace are sometimes counted to determine a turtle’s age, just like the rings in a tree trunk can be counted to determine life span.
Even though there are hundreds species of tortoises and turtles, and they nearly cover the earth living in all regions except the Arctic, these reptiles are endangered, threatened or facing extinction. In Illinois, there are 17 species of turtles — four are endangered or threatened, including the Blanding’s turtle.
Environmental factors make it hard for these turtles to survive in the wild — only 2 percent reach maturity. Brookfield Zoo is collaborating with the Illinois Department of Natural Resources and the DuPage Forest Preserve to nurture Blanding’s turtles in a protected off-exhibit pond at the zoo.
« This captive breeding program will enable us to release turtles into the wild, » Snider said, adding the zoo has many off-exhibit programs to help all types of animal species.
Snider identified the zoo exhibits that feature turtles and tortoises — the Swamp, Feathers and Scales, Reptiles and Birds among them. « We have a couple of Galapagos tortoises, some that were hatched here, » he said. About five years ago, young zoo patrons selected names for these tortoise babies.
Snider said the zoo has plans to expand its reptile collection.
Want to learn more about turtles? Brookfield Zoo will host a two-hour class in June that will include a visit to the Blanding’s turtle pond. Called « Life at the Pond, » this program is designed for children ages 5 to 8 accompanied by an adult. Find out about more classes and summer camp at the zoo’s website, www.czs.org.