Watch Planet Earth S01E04 live on the web
David Attenborough looks at the world's caves, including the Lechuguilla Cave in America, which contains chambers filled with 6m-long crystals.
He observes creatures in Texas and Thailand that never see daylight, and inside Deer Cave in Borneo he finds five million bats whose droppings support an entire ecosystem.
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Broadcasts and Catch Up TV for Planet Earth S01E04.
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Previous broadcasts on TV
Broadcasts in 2019
12/01/2019 at 18:00
12/01/2019 at 15:00
Broadcasts in 2018
27/12/2018 at 18:00
27/12/2018 at 13:00
11/11/2018 at 19:00
10/07/2018 at 14:00
26/05/2018 at 16:00
26/05/2018 at 10:00
03/05/2018 at 13:00
19/03/2018 at 14:00