美丽非洲大裂谷英文全文.docx
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美丽非洲大裂谷英文全文
1
RAINPATTERSGENTLY
2GRUNTS
3It'sraining...again.
42.5milesupinAfrica'sVirunga
mountains,
5theweatherismostlymiserable.
6There'snopointlookingforshelter.
7Theresidentgorillas'fur
8isthickenoughtokeepthemwarm,
evenwhenit'swet.
9Forsunlovers,
10theVirungaswouldn'tratehigh
asaholidaydestination.
11
Butwithoutthisrain,
12
thegorillaswouldn'thavefood
insuchabundance.
13
Andtherewouldbenograss
ontheplainsbelow.
14
THUNDERRUMBLES
15
WILDEBEESTLOW
16
AcrossAfrica'svastRiftValley,
17
it'swheretherainfalls
andhowitinteractswiththe
landscape
18
thatdetermineswhowillprosper
andwhowilldie.
19
Spanning3,000milesalongthelength
ofEastAfrica,
20
theGreatRiftisacomplex
ofenormousvalleys,
volcanoesandgrassyplains.
21
TheGreatRiftwascreated
22
whenaplumeofsuper-hotlava
pushedupbeneathAfrica
23
overmillionsofyears.
24
Butoncethewholeareahadbeen
liftedmorethanamilehigh,
25
cracksappearedaroundthemargins...
26
..creatingtheEasternRift
ononeside...
27
..andtheWesternRiftontheother.
28
Inthegiantclefts
oftheRiftValley,
29
watercollectsinvastlakes,
30
hometodazzlingarrays
ofcolourfulfish.
31
THUNDERRUMBLES
32
TheRift'srain-drenchedmountains
inturnfeedAfrica's
mightiestrivers,
33
whosetributariesprovidealifeline
forthirstygameintimesofdrought.
34
Butnotallthefreshwaterhere
isgoodforlife.
35
Ashfromvolcaniceruptionsturns
theshallowlakesoftheEasternRift
36
intocausticdeathtraps.
37
Atitsnorthernend,theGreatRift
plungesintotheRedSea,
38
creatingadazzlingworldofcoral
39
andoceantrenches
hidingdeepsecrets.
40
FewplacesonEarthprovide
sucharangeofaquatichabitats.
41
Sohowhaswildlifeadapted
42
tothechallengesandopportunities
oftheGreatRift'swateryworlds?
43
HIPPOSBELLOW
44
AllthewaterintheRiftbegins
asrain.
45
Convergingtradewinds
createcloudmasses
46
whichmoveupanddown
thelengthofAfrica,
47
producingtworainyseasons
eachyear,
48
bringingthelandscapetolife.
49
Attheendofthelongwetseason,
theRift'sriversarebrimful
ofwater.
50
There'sabundantfoodforthehippos
andotherriversideresidents.
51
Butthegoodtimes
won'tlastforlong.
52
Astherainsretreatnorthwards
andthegrasslandsdryandwither,
53
drinkingwaterbecomes
increasinglyscarce
54
fortheGreatRift's
wildinhabitants.
55
Inthesavannas,
lakesandpoolsevaporate
56
untilonlytheriversremain.
57
Theincreasinglyaridlandscape
posesaproblemfortheseAfrican
buffalo.
58
Becausedrygrassisdifficult
todigest,
59
eachbuffaloneedstodrink
34litresaday.
60
Asthegrazingclosetotheriver
isusedup,
61
theyfacealongerandlonger
dailytrek
62
betweentheirfeedinggrounds
andwateringplaces.
63
Buffaloescansmellwater
fromalongwayoff
64
andfollowestablishedtrails
throughthebush
65
whichleadtofavouritedrinking
spots.
66
Asthebuffaloesdrink,
flutteringoxpeckersgetachance
67
toremoveticksandotherparasites
fromtheirfaces.
68
It'stheonlytimetheywilltolerate
69
sharpbeakspickingaround
sensitiveeyesandears.
70
TRUMPETINGANDGRUNTING
71
Elephantsareevenmoredependent
ontheriver.
72
Inthishotclimate,
anadultelephant
73
needstodrinkastaggering
200litresadayjusttosurvive.
74
Thisfamilysharetheirfavourite
drinkingspotwithotherelephants.
75
Soaswellasslakingtheirthirst,
76
theriverprovides
afocusfortheirsociallife.
77
Rivermudprovidesexcellent
protection
againsttheAfricansun.
78
Withabellyfullofwater
andacoatofsunscreen,
79
theelephantsheadoff
towardstheblisteringsavanna.
80
Whilethefallingwaterlevel
isbadforelephantsandbuffaloes,
81
it'sjustwhatthesebee-eatersneed.
82
Theydigtheirnestingburrowsinthe
verticalbanksofRiftValleyrivers,
83
whichareonlyexposed
inthedryseason
oncewaterlevelshavefallen.
84
BEE-EATERSTWITTER
85
Threemonthsago,thisentire
nestingsitewasunderwater
86
andthebirdswerefaraway
inthejunglesoftheCongo.
87
Nestingonanexposedmudcliff
makesthebee-eatersnervous.
88
Andwithgoodreason.
89
AnAfricanfisheagle
hastakenupresidence
onthebank-top.
90
Butit'snotheretoadmiretheview.
91
Fisheagles'hugefeet
92
aredesignedtograbslipperyfish
fromthewatersurface,
93
buttheyaregoodforotherpreytoo.
94
Theshrinkingriverscreateaserious
problemforanotherRiftresident.
95
Hippos'dependenceonwateris
absolute-theyonlyfeelsafe
96
whereit'sdeepenough
forthemtosubmergecompletely.
97
Hipposfeedatnight
98
andspendthedaydigestingtheir
dinnerinthesafetyoftheriver.
99
Whilethegrown-upssnooze...
100
..theyoungstersplay.
101
Younghipposareverycurious.
102
HISSES
103
Astherivershrinks,
104
thehipposcrowdtogetherinthefew
remainingdeep-waterpools.
105
Eachstretchofriver
iscontrolledbyadominantbull,
106
whotoleratesotherhippos
inhispatch
107
solongastheybehavethemselves
anddefertohim.
108
Keepingyourheaddownandbottomup
whilesprayingdunginalldirections
109
countsasgoodmanners
inhipposociety.
110
Butjostlingyourneighbour
isconsideredverybadbehaviour.
111
Anyruckusinsuchcrowdedconditions
spreadslikeashockwave,
112
causingamultiplepile-up
ofgrumpyhippos.
113
It'sbadnewsforthehippo
attheend
114
whogetspushedintothepath
oftheresidentbully.
115
Oncethepeckingorderhasbeen
restored,everyonecansettledown.
116
Butthere'sadarkerside
tolifeintheRift'sriverworld.
117
Atthepeakofthedryseason,
118
ananthraxepidemic
sweepsthroughthecrowdedcolony,
119
killingdozensofhippos.
120
Thesmellofdeath
carriesinthecurrent.
121
Withinafewhours,thehippocarcass
122
hasattractedmorethanahundred
crocodilesfromfardownstream.
123
Crocs'ultra-efficientimmunesystem
124
allowsthesereptilestoeatdiseased
meatwithoutgettingsick.
125
Thesmallercrocshangback
whiletheireldersguzzleandgulp...
126
..shadowedbyahopefulheron
onthelookoutforfish.
127
Butit'sthecrocs'day.
128
Lifeanddeathareneverfarapart
inthewatersoftheGreatRift.
129
Butnoteverylakeorriver
130
isatthemercyoftheseasons
andthesun.
131
BeneaththeGreatRift'srolling
hills,
132
porousvolcanicrocks
channelwaterdeepunderground,
133
sometimesformanymiles.
134
Thesubterraneanwater
eventuallypopsoutasaspring,
135
likethisoneatMzima
insouthernKenya,
136
feedinganoasisofcrystal-clear
streamsandlakes.
137
Becauseit'ssuppliedfrom
alargeundergroundreservoir,
138
avolcanicspringlikeMzima
continuestoflow
139
evenattheheightofthedry
season...
140
..providingayear-roundhaven
forwildlife.
141
SNORTS
142
AndtheRift'suniquegeology
143
hasproducedanotherkind
ofwatersupply
144
that'sequallyimmunefromdrought.
145
Plungingsixmilesdeep,
146
LakeTanganyikaisAfrica's
greatestnaturalreservoir.
147
Itcontains30trillionlitres
ofwater...
148
..andstretches400miles
alongtheWesternRiftValley.
149
Itssisterlake,Malawi,
hasasimilarprofile.
150
LakeMalawiisfamousforits
extraordinarydiversityofcichlids.
151
Morethanathousanduniquevarieties
foundnowhereelseonEarth.
152
Allarebelievedtobedescendedfrom
justahandfulofspecies
153
whichhaveevolvedadazzlingarray
ofshapes,coloursandbehaviours.
154
00:
18:
17,600-->00:
18:
20,040
Thekeytothisexplosion
ofevolution
155
liesinthecichlids'
peculiarbreedingbehaviour.
156
Unlikemostfish,whichrelease
theireggsintoopenwater,
157
cichlidstakegreatcare
oftheiryoung.
158
Somesandybottomspecies
buildvolcano-shapednests
159
wherethemalecourtshisfemale,
160
thenguardsherbrood
161
untiltheyhavegrownbigenough
tolookafterthemselves.
162
Otherbabycichlidshave
atrulybizarrerelationship
withtheirmother.
163
Whenthreatened,
theytakeshelterinhermouth.
164
Shethencarriesthemaround,
waitinguntilthecoastisclear
165
beforereleasingthem
backintoopenwater.
166
Suchintensiveparenting
167
meanscichlidsoftenstayinonespot
throughouttheirlives,
168
forminginbredcommunities
whichturnintouniquelocalspecies.
169
Andthatexplains
whyLakeMalawiisfilled
withsomanydifferentcichlids.
170
Forlittlefish,therockylake
marginisadangerousplace.
171
Afamilygroup
ofAfricanspot-neckedotters
172
setsouttohuntalongtheshoreline.
173
Asnightfalls,thelake'sfish
faceaformidableenemy.
174
Pack-huntingnyandafish,
1.5mlong,behavelikesharks,
175
usinganelectricalsense
176
tohomeinonthelifesigns
ofsmallerfish
hidingamongtherocks.
177
It'sthoughttheycaneven
communicatewithelectricalsignals,
178
tosynchronisetheirfeeding
inthedark.
179
Fortheirprey,
there'slittlechanceofescape.
180
Furtherfromshore,
181
LakeMalawiplummets
intopermanentdarkness
182
beyondthereachofhumandivers.
183
Untilnow,no-onehasseen
whatlivesdownthere.
184
Aremote-controlledsub,
armedwithcamera,lights
andfishbait,
185
providesthefirstglimpse
ofwhatliesbelow.
186
Over100mdown,thefishbait
attractsdeepwatercichlids...
187
..buttheirteethcan'tgetthrough
itsarmouredskin.
188
Attractedbythesmelloffood-
alakecrab.
189
In
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