Content provided in partnership with

Experiment of the month

Natural History, Feb, 2003 by Stephan Reebs

When marine biologist Scott A. Eckert first tracked the deepwater dives of leatherback sea turtles in the Caribbean, his data told him the animals were spending middays at or just below the surface. He presumed they were basking in the sunshine, as reptiles often do. Eckert, who is a member of the scientific staff at the Hubbs Sea World Research Institute in San Diego, had attached depth recorders to the turtles' shells, but the instruments were naturally silent about the turtles' horizontal movements. Not entirely satisfied with his assumptions, he decided to verify them.

Most Popular Articles in Reference: The importance of understanding organizational culture; Credit card attitudes and behaviors of college students; What factors attract foreign direct investment?; Libraries Need Relationship Marketing - mutual interest marketing concept, ...; How to set performance goals: employee reviews are more than annual critiques; More »

Leatherbacks dwell primarily in the open ocean, but in their breeding years the females drag themselves onto beaches fairly regularly to lay their eggs. When seven females came ashore to nest on Saint Croix, Eckert fitted each one with a harness that included a custom-built marine speedometer. At sea, if a turtle surfaced to soak up the rays, the speedometer would pop out of the water, the recording device would pause, and the logged speed would drop to zero. (In earlier attempts to measure swim speeds, boats followed the turtles, a technique that some biologists suspected could have altered the turtles' behavior.)

Ten days later, when the turtles returned to their onshore nests, Eckert retrieved the data loggers. Contrary to his expectations, they showed that the leatherbacks never loafed: they swam almost constantly, day and night, at about a mile and a half an hour. At night they often dived for jellyfish, but in the middle of the day they glided horizontally about six feet underwater--deep enough to avoid the push and pull of the waves, yet shallow enough to perhaps orient themselves to the sun as they traveled between foraging sites. ("Swim speed and movement patterns of gravid leatherback sea turtles [Dermochelys coriacea] at Saint Croix, U.S. Virgin Islands," Journal of Experimental Biology 205:3689-97, December 1, 2002)

Stephan Reebs is a professor of biology at the University of Moncton in New Brunswick, Canada, and the author of Fish Behavior in the Aquarium and in the Wild (Cornell University Press).

Experiment of the month

Natural History, Feb, 2003 by Stephan Reebs

Find Research Guides for:

Find Featured Titles for: Arts

Most Popular Articles in Reference

Most Popular Publications in Reference