PLANET EARTH: CAVES (TV)
Summary
One in this scientific documentary series exploring the many wonders of planet Earth.
This installment focuses on caves around the world. Several base-jumpers parachute into Mexico's Cave of Swallows, the largest known cave shaft in the world, while down below cave glowworms attract prey with elongated lines of "silk" that produce a ghostly light. Limestone covers 10% of the Earth's surface, and mildly acidic rainwater carves into rock over the millennia and creates caverns, such as the Deer Cave in Malaysia, home to thousands of wrinkle-lipped bats, whose droppings provide food for the cave's roach population – which are in turn hunted by centipedes. As the cave is devoid of sunlight and therefore has no plant life, the bats depart the cave once a day to hunt insects, exposing themselves to falcon, hawks and other predator birds. The caves are also home to swiftlets, tiny birds that use bat-like echolocation to navigate in the dark, and their perilously perched nests, made of their own saliva, are regularly harvested by humans to create birds'-nest soup.
Stalactites and stalagmites are created inside the caves via the gradual drip of water containing dissolved limestone, eventually forming columns. The Yucatan peninsula has no lakes or streams, so the Mayan people of the 16th century relied on the freshwater wells found deep in Mexico's caves. Divers use strings to navigate the vast underwater areas of the caves, aware that they can easily run out of oxygen or become trapped in a "squeeze." As salt water does not erode limestone, sea caves are formed by the pounding of waves, as found on the islands of New Zealand and Australia, where snakes use bats' thermal energy to find and eat their prey in the dark.
In Thailand, isolated caves are home to a variety of troglodytes, including bacteria-eating angelfish and Texas cave salamanders, which have evolved to be eyeless after generations in the darkness. Mexico's Cueva de Villa Luz is home to many fish despite being full of sulfuric acid, both in the water and dripping from above. The desert of New Mexico is home to the world's "most secret" cave system, explored for the first time in 1986: cameramen spend 10 days exploring the Leghuguilla Cave, the eighth-longest in the world, finding "galleries" of elaborate formations of gypsum crystals, including the impressive "chandelier ballroom." As the desert has little rainwater, the cave and its "decorations" were created by sulfuric acid, and a form of bacteria provides an eerie glow untouched by the sun. The program concludes as the camera crew explains how they entered the heavily protected caves and shot the unique footage.
Details
- NETWORK: Discovery
- DATE: April 22, 2007 9:00 PM
- RUNNING TIME: 0:43:49
- COLOR/B&W: Color
- CATALOG ID: 110154
- GENRE: Public affairs/Documentaries
- SUBJECT HEADING: Public affairs/Documentaries; Science/Nature; Caves
- SERIES RUN: Discovery Channel - TV series, 2007
- COMMERCIALS: N/A
CREDITS
- Maureen Lemire … Executive Producer
- Huw Cordey … Producer
- Shannon Malone … Producer
- Kathryn Jeffs … Assistant Producer
- Alastair Fothergill … Series Producer
- Sigourney Weaver … Narrator
- George Fenton … Music by
- BBC Concert Orchestra … Theme Music by