The leatherback turtle is the largest of the seven species of sea turtles. It can reach a length of almost 9 ft and weigh almost a ton. The name for the leatherback turtle in Spanish is Las Baulas. There has been a decrease in the number of nesting females from 115,000 in 1980 to between 20 and 30 thousand in 1992. A serious problem with this species is the destruction of their nesting habitat.
In 1991 the president of Costa Rica attempted to establish a National Park in Guanacaste Province. There is strong opposition to the formation of a national park and strong foreign interests do not want to see the development of a park so that they can build hotels on the beach. At the present time the tenuous Las Baulas de Guanacaste National Park in Costa Rica protects the world's third largest nesting beach for leatherbacks. Since female leatherbacks come back to nest approximately every three years, and each year 1500 females nest in this region, a total of 4500 turtles nest in this critical region during each three year nesting cycle.
Leatherback turtles are pelagic animals. The females return to the beach briefly to nest up to eight times each nesting season at approximately 10 day intervals. Once the male leatherbacks enter the sea they never touch land again.
The diet of the leatherback consists primarily of jellyfish. Their sole dependence on this particular food source has contributed to their demise because of their ingestion of transparent plastic bags which they mistakenly consume as food.
The migratory paths of this largest ocean going reptile is unknown at the present time. They have been found from the equator to north of the Arctic circle. Unlike most reptiles the leatherback turtle is not a "cold blooded" animal but is able to maintain a body temperature above that of its environment. This mammalian-like trait gives it the ability to have a global distribution.
It is not certain what cues the animals use while migrating but preliminary information suggests the animals may be following deep water topographic features.
Our present study was designed to determine the migratory paths of animals which nest on both the Pacific and Caribbean coasts of Costa Rica. With support from the National Geographic Society and Project Earthwatch, Dr. Frank Paladino from Purdue University, Dr. Edward Standora from the State University College at Buffalo, and Stephen Morreale from Cornell are cooperating on this project. We attached satellite transmitters to two nesting females two weeks ago at the nesting beach in Guanacaste Province. These transmitters were specially designed with depth sensors to monitor the swimming and diving behavior of these animals. Some preliminary data suggest that these animals may dive to over 1000 meters.
Our plans are to plot the movements of these animals using the latitude and longitude readings provided by the orbiting satellite which receives signals from the turtles when they are at the surface. We are presently working on computer programs to decode diving information and will provide this as it becomes available.
CHALLENGE QUESTION:
FOR CLASSROOM DISCUSSION:
RESOURCES:
Sea Turtle Biology
Natural History, March 1992. p. 29 35. "Bound for Deep
Water: Leatherback Turtles Can Pursue Their Prey Half a Mile
Straight Down", by Scott A. Eckert.
Earth, February, 1995. p.34-38. "Earthly Attractions: Sea Turtles Are Uncanny Navigators". Summarizes new research findings regarding sea turtles' use of the earth's magnetic field for navigation.
Sea Turtle Conservation
National Wildlife, April-May, 1992. "Pulling Turtles Out of the Soup",
by Jim Watson. Describes efforts in the United States to protect
loggerhead turtle nesting beaches.
National Geographic, February, 1994. Pages 94-120. "Sea Turtles in a Race for Survival". An excellent summary of sea turtle conservation, including the work of our scientists.
The Nature Conservancy News, May-June, 1994. "Cast Ashore: Florida Sea Turtles' Search for a Safe Haven", by Leslie Allen.
Dr. Standora's Publications
Environ. Sci. Technol., Vol.26, No. 3, 1992. "Tracking
Endangered Species". by Frank V. Paladino, Edward A. Standora and
Stephen J. Morreale
Herpetologica, 40(2), 1984. p. 169 176. "Body Temperatures, Diving Cycles, and Movement of a Subadult Leatherback Turtle, (Dermochelys coriacea)", by Edward A. Standora et al