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Science Frontiers ONLINE No. 76: Jul-Aug 1991 |
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Eight Leatherback Mysteries
Our subject here is the leatherback turtle. Weighing up to 1600 pounds, it is the largest of the sea turtles. It is also the fastest turtle, hitting 9 miles per hour at times. But weight and speed are not necessarily mysterious; here are some characteristics that are:
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- The leatherback is the only turtle without a rigid shell. Why? Perhaps it needs a flexible shell for its very deep dives. What looks like a shell is its thick, leathery carapace -- a strange streamlined structure with five to seven odd "keels" running lengthwise.
- These turtles are warm-blooded, and able to maintain their temperatures as much as 10°F above the ambient water, just as the dinosaurs apparently could.
- The bones of the leatherback are more like those of the marine mammals (dolphins and whales) than the reptiles. "No one seems to understand the evolutionary implications of this."
- Leatherbacks dive as deep as 3000 feet which is strange because they seem to subside almost exclusively on jellyfish, most of which are surface feeders.
- Like all turtles, leatherbacks can stay submerged for up to 48 hours. Just how they do this is unexplained.
- Their brains are miniscule. A 60-pound turtle possessed a brain weighing only 4 grams -- a rat's weighs 8!
- Leatherbacks' intestines contain waxy balls, recalling the ambergris found in the intestines of sperm whales.
- The stomachs of leatherbacks seem to contain nothing but jellyfish, which are 97% water. Biologists wonder how the huge, far-ranging leatherback can find enough jellyfish to sustain itself.
(McClintock, Jack; "Deep-Diving, WarmBlooded Turtle," Sea Frontiers, 37:8, February 1991.)
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