BBC Wildlife - UK (2020-05)

TheExplainer

L

ifehasanextraordinaryability

toekeoutanexistenceinthe

mostunlikelyandinhospitable

environments.Thebottomofthe

deepestoceantrenches,thehottest

desertsandcoldesticecapsallsupport

life,evenif it’ssometimesjustthe

microscopic,single-celledvariety.

Butthereis oneplaceonEarth

whereit doesseemthatnothingat

allcansurvive.Atfirstglance,the

ponds in the crater of Dallol volcano

innorthernEthiopiaseemtoteem

withlife.Buttherainbowcoloursare

theresultofchemicalprocesses,not

biologicalones– theboiling,saline,

acidicwatersspewtoxicgasesand

containmagnesiumsaltsthatdestroy

biologicalmolecules.It’sworth

bearingDallolinmindaswesearch

forsignsoflifeonotherplanets.The

presenceofwater,it seems,is nota

reliableindicationthat life is possible.

Stuart Blackman

Isanywhere on Earth devoid of life?

Whyaregiantpandasbornsotiny?

GEOLOGY

A

newbornpandacubtypically

weighsabout100g,which

is gettingonfora thousandth

thesizeofitsmother.Among

mammals,onlykangaroosand

othermarsupialsareborn

smaller,relativetotheir

parents,buttheyhavethe

luxuryofcontinuingtheir

developmentsafein

theirmother’spouch.

It’ssomethingof

a mysterywhy

pandasareborn

sominuscule.

Onetheoryis

that it may be

connectedwiththeirlow-energy

bamboodiet.Anotheris thatit’s

theresultofbears’tendencyto

hibernate,becauseif pregnancy

overlapswithhibernation– during

whicha femaledoesnotfeed–

producinga largercubmightbe

toobiga drainonherresources.

Indeed,otherbearspeciesalso

producerelativelysmalloffspring,

albeitnoneastinyasinpandas.

Unfortunatelyforthistheory,giant

pandasdon’tthemselveshibernate,

thoughit remainspossiblethat

smallbabiesarea legacyinherited

froma hibernatingancestor.

Stuart Blackman

BIOLOGY

Scorpionscanbreathe

easy due to book lungs.

Animalshaveallmannerof

structuresforextractingoxygen

fromtheirsurroundingsand

excretingcarbondioxide.Wemay

bemostfamiliarwithlungsand

gills,butspidersandscorpions

havebooklungs.Theseare

enclosedinpouchesunderthe

body,andarenamedfortheir

resemblancetothepagesofa

looselyboundbook,between

whichaircancirculate.It is

thoughtthattheyevolved

fromthegillsfoundonthe

undersideofanaquatic

ancestorthatwassimilar

tohorseshoecrabs.

Stuart Blackman

Book lung

Panda: Katherine Feng/Globio/MINDEN/NPL; Dallol: Eric La

orgue/Art in All of Us/Corbis/Getty; squid: Solvin Zankl/NPL; scorpion: iStockphoto/Getty

Minime:baby

pandasareborn

sosmallthatthey

canbeatriskof

beingcrushedby

their mothers.

Someenvironments

arejusttooharshfor

anything to survive.

Q&A

88 BBC Wildlife May 2020