BBC Wildlife - UK (2020-04)

3 questionson

1

HOWDOWOODLICE

STARTLIFE?

Thesecommonorgardencrustaceans

arelive-born,hatchingfromeggs

retainedinsidethefemale.Thebabies,

calledmancas,hatchintoa moistpouch,

themarsupium,whichformsbetween

themother’slegs.Shecarriesthe

0.5mmbabies,all15–30ofthem,

fora dayortwo.Whenset

free,theyhavesixmain

bodysegmentsand 12

legs.Withina fewhours,

theymoulttorevealan

additionalbodysegment

and two more legs.

2

HOWLONGDOTHEYLIVE?

Mostwoodlicesurviveoneortwo

years,butincaptivity(yes,somepeople

reallydokeepthemaspets)individuals

willoccasionallyreachthegrandold

ageoffour.Aswoodlicegrow,fromthe

mancastagetosexualmaturity,they

mustmoultrepeatedly.Eachtime,they

discardtheirclose-fittingshell

toallowa newouterlayerto

expandandharden.The

shellseparatesfromthe

bodyandisshedintwo

halves,firstthefronthalf,

thenthebackportion a

few days later.

3

WHYDOWOODLICE SMELL

OFURINE?

Woodlicearedescendedfrommarine

crustaceans,whichejecttheirbodies’

harmfulwasteproducts,including

smellyammonia,intothewater.Land

animals,however,combineammonia

intonon-toxicurea.Thisisdissolved

inwater,thenpassedasurine.But

woodlicecan’tdothat,asthey’re

vulnerabletodryingout– it’swhythey

huddleunderdamplogsandflowerpots.

So,theycontinuetoexcreteammonia

butviagasexchange.Hence,their

huddlessmell.TheDutchforwoodlice

is ‘pee-in-the-bed’.Richard Jones

We i rd a n d won de rf u l woo d l ice

CETACEANS

Whydon’twhales

get the bends?

T

heydo!Justnotveryoften.

Whalescansufferthesame

DCS,ordecompressionsickness

(AKAthebends),ashumans.

However,beinghabitualdeep

divers,they’rebetteradapted

toavoidthisexcruciatingand

potentiallylife-threatening

condition.Scientistsarefinding

thatmarinemammalscancollapse

partsoftheirlungswhendiving,

andit’sthoughtthatthisreduces

theamountofnitrogendiffusing

intotheirbloodat depth,where

thehighpressuresmakegases

moresoluble.Thebendsoccurs

whenananimalascendstoofastto

the shallows, where the pressure

is lower,causingthedissolved

nitrogentoformbubblesin

theblood,tissuesandjoints.

It hasbeenlikenedtothe

fizzingwhenyouopen

a sodabottleandthe

pressureis released.By

collapsingtheirlungs,

whalesensureless

nitrogengoesin,so

lesscomesbackout

onthewayup.Signsof

DCShavebeenfoundin

whalesthatunderwentautopsies

afterstrandingincidentslinkedto

navysonar,suggestingtheywere

stressedandmayhaveascended

too quickly.Ellen Husain

Short-finnedpilotwhales

havebeenknownto

reachdepthsofabout

1,000mwheninsearch

oftheirfavouritedeep-

sea prey – squid.

April 2020 BBC Wildlife 83

Q&A