Planet Earth Is a BBC Production with Five Episodes in the First Series, and a Second Series to Follow in 2007

A STUDYGUIDE bY Andrew Fildes

www.metromagazine.com.au www.theeducationshop.com.au Overview

Planet Earth is a BBC production with five episodes in the first series, and a second series to follow in 2007. Each episode examines a range of environments, focussing on key species or relationships in each habitat, the challenges they face, the behaviours they exhibit and the adaptations that enable them to survive. Recent advances in photography are used to achieve some spectacular ‘first sights’ – in particular, stabilized aerial photography gives us remarkable views of migrating animals and the techniques used by their predators to hunt them. The series is suitable for middle secondary students studying Science and SOSE/HSIE, and for senior secondary students of Biology, Environmental Science and Geography. SCREEN EDUCATION

Episode Four: Caves selves in one of the most dangerous to protect the formations and the envi- sports around. Half flooded sea caves ronment of the cave, this is one of the The Caves episode begins dramatically in New Zealand provide haven for first detailed views we have had of this as a man hurls himself into the void of huge shoals of fish every night while amazing cave and possibly the last. the Cave of Swallows in Mexico. We nocturnal fish emerge from the cave soon realize that he is a base jumper each night in their turn. Web Resources and we watch as he and his friends parachute down into the largest cave Many cave dwellers have special Deer cave shaft in the world, 400 metres deep. abilities to make life in the dark pos- – http://www.ecologyasia.com/ Caves are one of the least explored sible, just as the bats and swiftlets use news-archives/2002/jul-02/ places on Earth and we rarely venture echolocation (sonar). A cave snake thestar_20020727_1.htm deep into them. If we do, we find that catches bats as they fly past by sens- Cave formation many animals and organisms have ing their thermal image and striking. – http://www.reec.nsw. made their home in the dark. Some animals choose to stay deep edu.au/2002/stu7-12/ in the dark for life and have changed cave%20ecosystems%20V3/ In New Zealand, tiny glow-worms hang irreversibly as a result. Troglobytes caves/textcave/4acavelf.htm from the roof of caves creating a galaxy like cave angel fish in Thailand who – http://dwb.unl.edu/Teacher/NSF/ of tiny, blue ‘stars’ in the eternal night. hang on to walls, feeding on bacteria C01/C01Links/rville.k12.mo.us/ The reality is less romantic as they in waterfalls; blind, white salamanders Cave/caveForm1.html are luring cave insects into the sticky which must detect even the slightest Remipedes strands of mucus that they dangle as movement to catch food; blind crabs – http://www.tamug.edu/ traps. Most large caves like those seen that pick through the debris to find any cavebiology/fauna/remipedes/ here are formed in the limestone that organic material to eat. There are the S_tulumensis.html covers ten percent of the land, lime- fish that live in the acidic waters of the Snottites stone that was once part of the seabed. Villa Luz sulphur cave and the colonies – http://www.nasa.gov/vision/ Acidic water literally dissolves the rock of bacteria on the walls, extremo- universe/solarsystem/cave_slime. to produce sometimes awe-inspiring philes, that exude sulphuric acid. Life html chambers such as Deer Cave in Bor- adapts to any environment it seems. Extremophiles neo, home to three million small bats. – http://www.astrobiology.com/ All the energy in the cave is brought in Finally we enter the most beauti- extreme.html by the bats – the enormous mound of ful cave system ever discovered, so droppings beneath their roost which is fragile that even scientists have to Species list literally seething with life. Swarms of seek permission to enter. Lechuguilla cockroaches feed on the guano and in the USA has walls covered with • Cave Glow-Worm – Arachnocampa anything else that falls from the roof, exquisite and delicate structures of luminosa (larva) dead or alive. The bats leaving the cave gypsum crystals up to six metres long. • Wrinkle-lipped Bat – Chaerenphon at twilight form an immense rolling As film crews are normally excluded plicata swarm which is promptly attacked by • Cave Cockroach – Pycnoscelus falcons and bat-hawks. The walls of the Episode 4: Caves Time Log striatus cave are also home to swiflets, small • Giant Cave Centipede – There- Intro 00:00 - 01:00 birds that use a similar echolocation upoda decipiens technique to the bats to find their nests Cave of Swallows 01:00 - 03:15 • Rufous-bellied Eagle – Hieraaetus in the dark. These are the bird’s nests New Zealand Glow-Worm 03:15 - 07:08 kienerii that are harvested for gourmet soup by Ha Long Bay 07:08 - 08:15 • Peregrine Falcon – Falco peregri- local villagers, hanging on to ropes and nus Deer Cave 08:15 - 12:25 makeshift ladders high above the cave • Bat Hawk – Machaerhamphus floor to collect the precious little cups. Bat Hunting 15:50 - 17:05 alcinus Cave Swiftlets 17:05 - 20:30 • Remipede – Speleonectes tulumen- In the Yucatan region of Mexico, there Limestone Formation 20:30 - 23:20 sis are no surface rivers or lakes, only a • Demoiselle (Damsel) Fish – Chro- Yucatan Cenotes 23:20 - 30:00 massive 500km network of flooded mis dispilus caves below the surface. Any rainfall Poor Knight Islands 30:00 - 30:55 • Cave Racer Snake – Elaphe taen- SCREEN EDUCATION sinks into the limestone rock and Cave Python and Bats 31:35 - 33:45 iura becomes part of these subterranean Troglobytes 35:35 - 37:25 • Texas Cave Salamander – Eurycea rivers. Just as with the base jumpers, troglobytes Villa Luz Acid Cave 37:25 - 44:15 this is an irresistible lure to adventur- • Belize White Crab – Typhlopseudo- ers, cave divers who explore and map Lechuguilla Cave 44:15 - 48:00 thelphusa acanthochela the system at enormous risk to them- (Timings are approximate) • Cave Mollies – Poecilia sphenops 1

Blackline Master | Planet Earth | Episode 4: Caves Viewing Questions SCREEN EDUCATION

1. How deep is the shaft of the Cave of Swallows? ��

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2. How do glow-worms catch insects? ��

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�� 5. How much of the rock on earth is limestone?

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�� 6. How are caves formed in limestone?

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3. What makes a glow-worm glow? ��

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�� 7. How many bats are in Borneo’s Deer Cave?

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4. What is limestone? ��

�� 8. What eats bat droppings? �� 1b

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9. Why do people collect the bird’s nests? ��

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�� 12. What is a cenote?

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10. What is a stalactite? ��

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�� 13. Why is cave diving so dangerous?

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11. How is a stalagmite different? ��

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�� 14. Why do demoiselle fish sleep in the sea caves?

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15. How do the cave snakes ‘see’ the bats? 18. What lives in the cave water?

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16. What is a troglobyte? 19. What hangs from the cave walls?

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�� 20. What mineral forms the crystals of Lechuguilla?

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17. Why is the water white in Villa Luz cave? ��

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Case Study | Planet Earth | Episode 4: Caves 'Closed' Ecosystems SCREEN EDUCATION

2a 'Closed' Ecosystems are Open Ecosystems. But in a few come from to start up the system? cases, it is difficult for organisms to The main source is the droppings The caves featured in this episode enter or leave – an isolated pond or of the bats and birds. They leave are unique in many ways. They con- oasis, for instance, or a cave. In one, the cave to eat outside and excrete tain entire and isolated ecosystems species are restricted by their need of inside the cave, providing food en- in which many odd species have water. In the other, by their ability to ergy for small invertebrate omnivores adapted to suit the habitat niches live in the dark. These odd examples like cockroaches, the grazers of the available. Some caves contain spe- are almost Closed Ecosystems – no cave. They are detritivores (detritus cies that are only found in that one system can be completely closed but = waste). Larger invertebrates like place and the ecosystem must have these come close. centipedes then eat the cockroaches been developing for millions of years while micro-organisms break down in that one isolated place for these In a normal ecosystem, the sun the cockroach wastes. It is estimated endemic species to develop. powers the growth of green material that the bats eat up to 10,000kg of which is then eaten by herbivores insects every night, bringing that Most ecosystems do not have and so on. Photosynthesis is the driv- energy into the cave. In more sealed boundaries that are easy to define. ing force. However, in the cave the caves, water flowing through may Animals and plants stray over any sun does not penetrate and nothing bring food sources like bacteria. border that we draw on a map. They grows, so where does the energy

Research Activities • Draw a food web of Borneo’s Deer Cave, based on the following information. » Bats and swiftlets – eat insects outside, excrete inside » Cockroaches – eat bat dung » Centipedes and whip scorpions – eat cockroaches » Cave cricket – eats bird eggs and nestlings » Cave racer snake – eats bats and swiftlets

Troglobytes and The true troglobytes who never leave Extremophiles – Extremophilic or- Extremophiles the dark are often strangely adapted. ganisms are usually eukaryotes and Animals like fish, salamanders and simple animals which have adapted Troglobyte – animals that live in crabs will often lose the pigment in to live in extreme environments. and never leave the cave. They are their skin and eyes as there is no These include the snottite bacteria in often specially adapted for life in the value to being coloured and their eyes the film which get their food from the dark and could not survive in a sunlit serve no purpose. Eventually, many toxic chemicals in the air of the cave habitat. In the Borneo area these have lost their eyes altogether and and exude strong sulphuric acid. It include blind, white crabs, millipedes there are many example of blind cave seems impossible to believe that any and pseudoscorpions. creatures. This means that they must organism could tolerate such condi- find their food by other means. Crabs tions but little cave fish live in highly Troglophile – animals that like caves can try and eat anything they find and acidic waters in huge numbers. In but can also live outside if neces- some fish like the angel fish are filter Antarctica, fish live in sea water so sary. Here these include the cave feeders, filtering nutrients out of the cold that they should freeze but they racer snake and the cockroaches, water that flows over them. Salaman- have a substance in their blood, drawn into the cave by the huge food ders in the outside world have poor an ‘anti-freeze’, which keeps them resource. eyesight and are sensitive to pres- unfrozen. sure so it is no surprise to find cave Trogloxene – animals that live in the salamanders who have lost their eyes Check some of the extremophiles

cave but leave it to feed such as the and developed extreme sensitivity to here: http://www.astrobiology.com/ SCREEN EDUCATION bats and swiftlets. any movement around them through extreme.html sensory nodes in their skin.

Research Activities • Gather examples of the following types – halophiles, thermophiles, xerophytes, acidophiles. • Prepare a report, poster or PowerPoint presentation that describes the different types, their environments and lifestyles. 3

Blackline Master | Planet Earth | Episode 4: Caves Cave Life (Senior Level Biology) SCREEN EDUCATION

10 3a

3. What do you think makes people go base jumping or Discussion Questions SCUBA diving in caves?

�� 1. The bats of Deer Cave are ‘microbats.’ How do they dif- fer from fruit bats (flying fox)? �� 4. How would you protect a very fragile cave like the Le- chuguilla from damage? ��

�� 2. What do you think that the main environmental threats might be to the Deer Cave ecosystem? �� SCREEN EDUCATION �� 5. How could the existence of extremophiles prove that life might exist on other planets? �� 11 3b

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�� B. Are there any caves in your area or within a couple of hundred kilometres? There are many examples of deep �� caves, flooded caves and sea caves around Australia and New Zealand. Find out where they are and what �� animals and ecosystems may live in them.

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Extension Tasks ��

A. Most people are not aware of the small bats around �� them but they are widespread. Find out which are the species in your area and where they hang out! Find out �� why they are all so ugly! ��

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Blackline Master | Planet Earth | Episode 4: Caves SOSE / Geography SCREEN EDUCATION

13 4a 2. Why do you think that some caves are permanently ‘One tenth of the land is limestone’ flooded?

As well as your notes from the episode, you will need to do �� some basic research on the web or in the library for some questions. ��

1. How are caves formed in limestone? Research and �� describe the exact process.

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3. How are the strange rock formations in limestone caves �� actually formed and how long does it take?

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4. Why is the Villa Luz cave poisonous – what is the rea- �� son for the acid water and atmosphere? �� Further Research Activities �� A. Are there any caves in your area or within a couple of �� hundred kilometres? There are many examples of deep caves, flooded caves and sea caves around Australia �� and New Zealand. Find out where they are and how exactly they were formed. �� 5. What is a halocline and why does it form? �� SCREEN EDUCATION �� B. Test the mechanism of acidic rainwater dissolving basic �� limestone rock. Take a small quantity of baking soda in a beaker and add some plain, white vinegar. Observe the reaction. The cave process is slower, but the same �� reaction. 15 ANSWER SHEET

Viewing Questions 18. Small fish called mollies live in the caves to prove how fit or brave acidic water they are or for the thrill of danger. 1. The Cave of Swallows is 400m deep 19. Bacterial colonies called snottites 4. The controlling body has decided 2. With a sticky thread and a glowing 20. Lechuguilla is festooned with to put very severe restrictions on lure gypsum crystals the number and type of people 3. A chemical reaction in a capsule in who enter. They must have a VERY the tail Cave Life good reason such as a genuine 4. Rock made from old marine shells scientific research project. The and corals 1 Flying foxes are large mammals BBC had great difficulty get- 5. Ten per cent of surface rocks which live entirely on fruit, usu- ting access. Some undamaged 6. Slightly acidic rainwater eats away ally roost in trees in tropical and forest areas in Australasia have the limestone sub-tropical areas and have no similar entry restrictions to reduce 7. 3 million sonar – they have large nocturnal inevitable damage but unlike them, 8. Cockroaches and crabs eyes instead. They are no relation the cave can’t regenerate. Any 9. Nests are collected to make bird’s at all to the hundreds of species of damage is permanent. nest soup insect-eating bats which are found 5. Many planets in the Solar system 10. Stalactites are rock ‘icicles’ de- all over the world. have environments that are extreme scending from the ceiling 2. Local people collect the birds but still within the limits of some 11. Stalagmites are mounds of calcite nests and disturb the swiftlets of these organisms on Earth. For forming on the floor when they do – many fledglings instance, a moon of Jupiter is be- 12. A cenote is the flooded entrance to and eggs are lost. They also col- lieved to have a liquid water ocean a cave (in Mexico) lect bat guano as fertilizer for their beneath its insulating crust of ice. 13. Because you can get lost in the farms. Recently, more and more Some of the organisms here could dark and run out of oxygen tourists have been visiting, pos- live in cold, dark, low oxygen water. 14. The fish use the caves as a refuge sibly bringing problems such as There may be similar life developed from predators diseases, and fungi on their boots. there – it is at least possible. 15. Snakes can ‘see’ their heat, a 3. A sense of adventure perhaps? thermal image People go to Deer Cave as tourists BBC and Planet Earth are trade marks of 16. A troglobyte is an organism that – it wouldn’t suit most. Equally the British Broadcasting Corporation and never leaves the cave some people seek personal chal- are used under licence. Planet Earth logo © 17. The cave water contains sulphuric lenges, to ‘triumph’ over extreme BBC 2006. BBC logo © BBC 1996 acid environments like mountains and

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