BBC: Life of Mammals. A Winning Design

BBC: Life of Mammals. A Winning Design

1 This is one of the coldest places on Earth – the high Arctic. Here the temperature drops to 50

2 degrees below freezing. If I have didn’t wear this …………………… the cold would kill

3 me in minutes. And yet there are animals that live here all the time. One of the most

4 remarkable is hunting just stay there. …………... The any reason that it and I don’t ………..

5 is that we are both mammals and have the mammal’s ability to use food to heat our bodies.

6 We are warm-blooded. And the reason that it is more at home here than I am is that it has

7 more of that other …………….. ………than I have. Its body is insulated ……….

8 Warm-bloodedness is one of the key factors that enabled mammals to conquer the earth.

9 And to develop the most complex bodies in the whole animal kingdom. In this series we will

10 travel the world to discover just how very and astonishing mammals are.

11 We go to Africa where mammals are ………….. Here ……………. with specialist

12 grass-eaters. And there are other mammals here too with different tastes. Some hunting

13 mammals have become ………. on Earth. And those they hunt have to respond or die.

14 Some mammals are become ………….. and aggressive. They fight for mates. They fight for

15 food. Some even have to fight for a place to live. Wherever you go you find …………….

16 of mammals. Some are miniatures a few inches long. Others are massive. And the biggest

17 of those on land are ……by those in the sea. I can see its tail just under my boat here. And

18 it’s coming up. Coming up! There! The Blue wave! It’s the biggest creatures that exists or

19 has ever existed on the planet! Mammals are as at home in the water as they are on land.

20 Some lounge around on the surface. Others prefer to do so on the beach. We will go

21 underground to track them. And up into the tops of the tallest trees. Mammals have even

22 taken to the air and challenged the birds. In some places they …….. in astronomical

23 numbers. They …. almost everywhere. And precisely how they do so depends as in so much

24 in life of mammals on what they eat. Between them they tackle everything that’s edible.

25 Some are very particular about their food. Others will simply take the best of what is around

26 at the time. And top of the menu right now is salmon. We will look at the lives of our

27 closest relatives. And they will lead us to ourselves. Perhaps the most successful variation

28 of the mammal’s winning design.

29 To …… the very beginnings of the mammalian dynasty we must travel to Australia.

30 I’m looking for one of the most ancient of all mammals. It’s so ancient it shares at least one

31 characteristic ………. It’s a very ………., but here in South Australia there’s a population

32 that have been fitted with radio transmitters. And I can track them ………... I’ve got a very

33 strong signal. At first glance you might think that this mammal is some of ………

34 or perhaps a porcupine. But actually it’s really different from a hedgehog, porcupine or any

35 other kind of mammal. It’s an echidna. And you can tell it’s a mammal because it’s got hair

36 and only mammals have hair. Indeed some of its hairs have been enlarged and strengthened

37 and turned into big spines which giving such ……….. This hair helps to keep the echidna

38 warm. Making sure that it doesn’t too much valuable body heat to the cold air.

39 The……..with which the echidna and every other mammal’s generate that heat is a food.

40 And on a cold winter’s day like this the echidna has to spend much time searching for its

41 next meal to make sure it’s fully stoked up. Also echidnas have ……… and excellent

42 hearing. It’s their sense which guides them to food. They …….. and grubs and then get

43 them by ripping open the nests and tunnels with their immensely strong close.

44 That ………into holes and then out comes a long sticky tongue that flicks ………… to lick

45 up whatever is worth eating. Echidnas are particularly found of ants and termites and will

46 even climb trees only to find them. This particular female has an unusually healthy appetite

47 because she id about to breed. And the way she does do is a reason why the echidna is such

48 a truly weird mammal. The echidna doesn’t give birth to live babies she lays an egg. It’s

49 hidden in her hair in a shallow depression on her underside. It’s no bigger than ……... Inside

50 it a young echidna is slowly developing. After her baby hatching she carries it around on

51 her underside for about 50 days until it begins to develop spines. She then posits it in a

52 barrow where it stays and grows for nearly seven months. But how does she feed it during

53 this long time? For the answer we need to find the only other egg-laying mammal in the

54 world today. And need too live here in Australia. Surfacing behind me here is one of the

55 most extraordinary animals in the whole world. So bizarre that when ……… first sent from

56 Australia to Europe people thought it must be a fake. But it’s not, it’s real, it’s alive, it’s a

57 platypus. That bull looks as it should belong to a duck. But it’s not hard like a bird’s big it’s

58 rubbery. Like the echidna the platypus feeds on small …….. but it looks under water. Once

59 it collected a mouthful it takes them to the surface and grand them ……... It doesn’t have

60 any teeth but there are horny plates in sight of bill do the job. But how does it find that food?

61 Underwater it closes its eye line tight so it can’t see anything. But it has a remote sensing

62 device it’s bill. As it sweep it side to side like a metal detector. Sensors in it pick up

63 ………… that given of by all living things. There were very few mammals on Earth 100

64 million years ago when the first platypus appeared. But there was another kind of animal

65 hunting in the rivers. Birds. As the platypus grabs around on the river bad. It attracts fish

66 which ……... Water birds are among the most ancient bird families so this really could be a

67 scene from those days just after the death of the dinosaurs when a new kind of animal can

68 appeared on Earth. One with warm blood and fur. The platypus has had enough. She is

69 having back home for her breeding burrow for where at the end of a tunnel that may be 20

70 yards long. Safe in a leaf line nesting chamber she’s laid an egg. Exactly what goes on

71 inside a nest no one really knew. No one had even succeeded in breeding platypus ………

72 until very recently and certainly no one at all had ever seen inside an occupied platypus’s

73 nest until now. We have bored a very carefully a hole into the nest that lies below here and

74 inserted this tube. This is ………. with a little light on the end. And I can manipulated like

75 this so I can scan it. If I then insert that inside this tube I’ll be able to see something that no

76 one has ever seen before. That’s her in close-up. That’s her eye, her ear.

77 It looks as though she’s seen us. She’s........... us. No, not worth eating. She doesn’t

78 seem particularly disturbed by it. But has her egg hatched? I think that........... may have

79 something to do with feeding. I’ll move the camera to see if I can see what’s going on.

80 Yes, there it’s milk.

81 Milk is the perfect food. It provides the growing youngster with everything it wants. Only

82 mammals produce milk. In most mammals, it comes from the nipple, but in this very

83 primitive mammal, it simply oozes through the skin.

84 She’s leaving. Off she goes. The end of her.................. What’s that among the leaves?

85 There it is, that’s her baby. I’ll try and zoom in on it. Now you can see it a tiny

86....................., naked and blind. On the end of its bill you can see a tiny spike. It’s an egg

87 tooth, used to cut through its shell, in the same way as reptiles and birds do. Only a few days

88 old.

89 The platypus and the echidna are the only mammals alive today that lay eggs, links with the

90........................... from which mammals are descended. Both are so well-adapted to their

91 particular ways of life that they are still successful and widespread in Australia.

92 Quite an achievement, for they’ve been around for 100 million years, as the fossil evidence

93 makes clear. Most of that evidence is just tiny fragments, but here in Riversleigh in northern

94 Australia, it’s a very different story. Fifty millions years ago, Australia was a much wetter

95 country than it is today, and just here was then......................... The bodes of animals that

96 died in or around those swamps became buried in limey mud at the bottom of the pools and

97 now are preserved........................ This rock is full of bone. Here’s the rectangular bony

98 plate from the back of the crocodile. The rest looks like bird bone. The limestone in which

99........................ is so hard that the only way to get them out is to put the whole block in a

100 bath of acid for a few weeks. The limestone than dissolves away and what is left is

101 sometimes extraordinary bones, beautifully preserved. This is the skull of an exstinct

102 platypus, about 15 million years old. It’s been called................, which means “enduring

103 tooth”, because, unlike today’s platypus, which has no teeth, this one still has them. There

104 are the empty moral sockets. There are two little pre-morals. What was this place like 15

105 million years ago, when Obdurodon was alive?

106 The night sky would have been full of the calls of animals in the surrounding lush tropical

107 forests. Obdurodon, like....................., would swim in the pools. In the trees around, there

108 were mammals of a different kind – marsupials. There were different kinds of possums,

109 similar to those alive today. On the ground, there were less familiar creatures, like this large

110 marsupial leaf- eater. Nothing like it is alive today. There were great numbers of small

111 mouse-sized animals which judging from their teeth, are insects...and others with a taste for

112 flesh........................................................., a marsupial lion. It was big enough to make a

113 meal of an unwary Obdurodon.

114 As the millions of years passed, Australia began to dry out. The rainforests retreated and

115 were replaced by grassy plains. As the landscape changes, so did the marsupial mammals.

116 They thrived and diversified into many different species and are still abundant today.

117 They differ from the platypus and echidna in reproduction. Instead of laying eggs, they

118 produce young without protective shells, and this....................... is about to do so. Out

119 comes, not a shelled egg, but a tiny, under-developed little worm. It weighs less than

120.................. It has no back legs but it has forelegs, just strong enough to pull it through its

121 mother’s fur. It has started on an extraordinary journey. To survive, it must get to a pouch

122 higher on its mother’s belly............................, this tiny living particle climbs upwards,

123 against the bull of gravity, towards the smell of the pouch. After about three minutes, it

124 reaches the lip of the pouch and clambers to safety inside. There it clamps its tiny mouth on

125 its mother’s nipple and takes its first meal, of milk. As it grows,.....................................

126 from the nipple change to ensure the infant gets exactly the nutrients it needs for each stage

127 of its development. By the time it’s nine months old, it’s getting cramped. It’s time to enter

128 the outside world. It’s almost like a second birth. He’s a little unsteady at first, but Mum

129 offers a helping hand. Now he’s known.............. It’s all a bit much for one day and he

130 heads back to the security of Mother’s pouch. It will another year before he’s fully

131 independent.

132 Other marsupials have taken to the trees koalas. They too have pouches. It’s the latin word

133 “ marsupium” meaning........................ that gives the whole group its name. When a koala

134 joey emerges, it clings tight to mother for several days before going solo. Koalas feed

135 exclusively on the leaves of gum trees, eucalyptus. They are hardly an ideal food. They’re

136 tough, indigestible and full of unpleasant chemicals. By sticking close to Mother, they learn

137 how to pick the best trees with the most palatable leaves...................................................so

138 they have to eat a lot of them and spend almost all their waking hours doing so. When not

139 feeding, they conserve their energies and sleep. Only koalas can live on a diet of these

140 particular gum leaves. Australia seems full of difficult diets...................................., but

141 there are marsupials that can deal with almost every one.

142 This vast continent stretches from the temperate and sometimes chilly south right up into

143 the tropics. In the centre, there are dry, sun-baked deserts, where it’s only too easy to die

144 from thirst. There are great moutains ranges, which in winter................................... But the

145 mammalian characteristics of warm blood and isulating fur enables the marsupials to cope

146 with almost anything.

147 The wombat’s fur is so thick it can remain active throughout the winter, even in the coldest

148 parts of Australia. It feeds on grass and other plants, and the strong front limbs with which

149 it digs itself burrows are equally good at clearing snow to find food. Its pouch opens................... so the youngster doesn’t get a faceful of snow as Mum digs for food.

150 Numbats live in woodland, but it can get cold at night and this family are warmimg

151 themselves in the early morning sun. Fur must be in prime condition if it’s to fuction as an

152 insulator............................. These dry eucalyptus forests look unpromising as a source of

153 food, but there plenty of termites. Numbats have just the right equipment to collect them,

154 have to kept well-anointed with sticky saliva, and numbats spend some time making quite

155 sure that it is. With gear like that, a numbat can collect.................... termites a day.

156 This creature’s ancestors might also have used their tongues to collect insects, but the

157 mammal tongue is an adaptable instrument and the honney possum usses it to gather pollen

158 and nectar. It’s one of the most specialised feeders of all mammals. Its tongue has a brush

159 on its which soaks up nectar from even the deepest flowers. These fields of boulders are

160 home to a less fussy marsupial, which will collect whatever food happens to be around. At

161 the moment, there's an unusual.......................................................... from the summer sun.

162 The mountain pygmy possum may be small, but it has a huge appetite. Moths provide a

163 fast-food snack, high in energy rich fat, and it will eat as much as it can while it can get it,

164 and put on a little fat to see it through................... Only the indigestable wings are

165 discarted. At other times of the year, it lives on berries and seeds, picking them off with its

166 nimble fingers. The striped possum has a particular taste for grubs. It lives in the few

167 fragments of rainforest that survive in........................... It's got what's necessary to collect

168 them- an excellent sense of smell, strong teeth to chew the bark and a long sticky tongue.

169 Perhaps the most challenging of all Australian environments is the arid hot desert at the

170 continent's heart. Here is little to eat or drink and few places to hide. But marsupials have

171 colonised this country too. Everybody would recognise those as kangaroos but the

172 kangaroos belong to a very big family.

173 There are........................................................., big ones and small ones. hese are red

174 kangaroos, the biggest of the families, and they are particularly at home in this drt country.

175 This can be one of the hottest places on Earth, so red kangaroos don't have to worry about

176 keeping warm. Their problem is over-heating. All mammals sweat to lose heat, but water is

177 in short supply here, and red kangaroos only do so when they’re on the move. Instead,

178 during the hottest part of the day, they are used of whatever shade they can find. Wiping

179 saliva on their forearms helps to lose unwanted heat. There’s a rich supply of blood vessels

180 near the skin surface, and as......................................, the blood cools. They only feed in the

181 morning and evening when it’s cooler. When they do, it’s hard not to notice the

182 extraordinary way by which they get around. The tail acts rather like a fifth leg, propping it

183 up as it swings forwards its huge hind limbs. It looks.................when they’re moving

184 slowly, but when a kangaroo senses danger, the advantage of these unusual proportions

185 becomes obvious. Hopping at full speed, a kangaroo.....................................They are the

186 only large mammals in the world that have developed this way of getting about but it is a

187 very efficient way of doing so.

188........................ in the back legs act like giant springs storing energy as it lands then releasing

189 it to propel the animal forward again. By recycling energy like this, kangaroos can quickly

190 cover vast distances to escape............................ or to search for food and water. And it is

191 not just out on the flat that hopping works well. Some marsupials even hop around on cliffs.

192 The rock wallaby’s key to success lies in its feet. The soles have thick corrugated skin and

193 pags which give them a grip on every kind of surface and a wallaby can bounce about this

194 difficult terrain............................................ There is little to drink here and though adults

195 get the fluid they need from their diet, growing youngsters may find that difficult. This

196 youngster is after an extra drink from its mother. They are able to bring up fluid from the

197 stomach to ensure their young don’t....................... It’s a special adaptation to this

198............environment.

199 Grey kangaroos live out on the relatively well- watered grassy plains. They are among the

200 most sociable of all Australian marsupials. But living in groups can lead to problems in

201 getting on together. Last season’s joeys are fast approaching independence. So the mother

202 will soon be ready to mate again. Males use their sense of smell to find out if a female is

203 sexually available and will court her for several days. Having found a promising one, the

204 male stays close to her side to try and ensure that he and no other male mates with her. The

205 most dominant male is likely to be the one to father most of the next generation and that is

206 something worth fighting for. Joeys also fight but it’s just play boxing- a way of learning

207 skills that will be important later. It’s not always a fair fight................................, this little

208 one still has mother to see off the neighbourhood bully.

209 Marsupials first appeared about......................................, towards the end of the age of the

210 dinosaurs. Then Australia was a part of................................ But as the millions of years

211 rolled by, that continent began to split apart. One fragment drifted south. That was

212........................... As it got closer to the South Pole, so it got colder, became covered in

213 snow and ice, and its animal inhabitants died out. A second part was........................

214 It drifted north and got warmer and marsupials flourished. But there was a third part. It too

215 drifted north. It too had marsupials, and they are still there. That was............................

216 It may have been in this region of the super- continent that the marsupials mammals first

217 appeared. Many eventually died out, but there are still a lot of survivors. This is one of the

218 most elusive of them. Living in........................... streams, it operates only at night, moving

219 in the pitch blackness by feeling its way with its front paws and.............................. It’s the

220.................., or water opossum. These pictures, taken with infra-red cameras, may be the

221 first time it’s been filmed in its natural environment. It’s hunting for fish and

222........................................ Its fur is so thick that its skin doesn’t get wet. It has webbed feet

223 to propel it through the water. It’s too dark for even the sharpest eyes to see very much. The

224 yapok relies on its acute sense of smell and hearing to locate its food. It swims with its

225 arms apart, groping for its prey with its highly sensitive fingers. It usually takes its catch to

226 the shelter of nearby vegetetion to devour it. It doesn’t only feed in the shallows. The

227 yapok has a large territory and there are many deeper pools in which to swim. Under water

228 it swims with its eyes shut, like the platypus and hunts entirely................... The female

229 yapok an also shut her pouch and does so with such muscular strength that water doesn’t

230 get in and drown her babies, though they must be close to suffocation after a few minutes of

231 fishing. After a good night’s hunting, the yapok.............................................

232 The yapok is the only...................... marsupial in the world. Most marsupials in Central and

233 South America live high..................... of the rainforest. Just how many there are up there,

234 no one really suspected untill scientists started using cranes, like this one. Such

235....................gives easy access to this high canopy that is now possible to get

236........................... of how rich wildlife is up here. And what we might think of Australia as

237 the land of the marsupials, in basis this canopy of the rainforest may have more of them

238 than any other kind of mammal. Most are strictly................, and though they are abundant,

239 they like everything else in the forest, can be difficult to spot. Many are similar

240..........................., tree dwellers with few specialisations and a broad diet which can include

241 flowers, fruits and insects. These marsupial mammals of course reproduce in just the same

242 way as their Australian relatives. They give birth to tiny babies at a very early stage in their

243 development. The pouch is seldom as well-formed as that of a kangaroo or koala but their

244 ……very well clinging unprotected to their mother’s underside. Marsupial mammals

245 dominate Australia and …… of Central and South America. But alongside them are living

246 a radically different kind of mammal. A kind which we ourselves belong. And it’s only that

247 kind that you find everywhere else in the world. The plains of Africa have …….. but not

248 one of them is a marsupial. They all reproduce in a fundamentally different way. This

249 ……… her baby within her her by means of a remarkable organ growing on the wall of her

250 womb a placenta. …….. rich in blood vessels that is connected to her baby by a cable the

251 umbilical code. So which she has fed her growing youngster. Blood vessels in the baby

252 blood run through the code of the placenta and …… to its mother’s they absorb nutrients

253 from her blood. And carry it back to the unborn infant. But all this is about to change.

254 Giving birth to such a large highly-developed baby passes ……… on the mother. It’s

255 pretty traumatic for baby too. But it’s a great advantage in being born this way. There are

256 plenty of animals around for whom a new-born calf would make a welcome meal. But this

257 mammal baby …… the help of a placenta is able to get to its feet within minutes of its

258 birth. And while it finding its balance its mother is there to defend it. Now the baby can be

259 fed in the same way as all mammal babies with its mother’s milk. Placental babies may

260 still have months even years to go before they are fully independent. But its early months

261 protected within mother’s body have given these babies an inevitable start in life. So

262 whether a mammal lay eggs or give birth to live young whether their babies develop in a

263 wound or in a pouch they are managed to live almost everywhere.

264 The warm-blooded, ………….. in all its multitudinous variations really is a winning design.

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