May 2020 BBC Wildlife 21WILD MAY
colony.Thisenablesit tobumble
aroundwithconfidence,dodging
betweentheants’legsandpretty
muchgoingwhereit pleases,
evenbeingtreatedlikea fellow
colonymember.
If anantwoodlouseis
transferredtoa differentcolony,
however,it behavesandis
treatedverydifferently.Fora
start,it runsmore– andit’s
fast,too.Thisinitialresponseto
disturbanceis oftenseenwhen
youexposeoneoftheseanimals
byturningoveritshidingplace.
Thewoodlousedashesawayto
hide,withitsflattenedantennae
quivering.Shouldspeedfail,the
antswillharangueit aggressively.
Nowyougettoseehowthat
broadcarapacecomesintoits
own,completewithflattened
epimera(theflangesthatstick
out to the side, giving a serrated
appearance).
When attacked, an ant
woodlouse hunkers down, tucks
in its antennae and becomes
immune to the ants’ collective
efforts. If the attack continues,
the woodlouse will raise the two
strange pointed organs on its
rear, known as uropods, from
which a liquid is excreted. This
has a repellent effect and turns to
a sticky goo, effectively gumming
upanant’smandibles.Iustrat
ons
by
Peter
Dav
dScott/The
Art
Agency
NICK BAKER
is a naturalist, author and TV presenter.Revealsafascinating
worldofwildlifethat
weo enoverlook.canscavenge,includingant
droppings,deadantsandthe
husksoftheants’insectprey.
Theantwoodlousewillalso
steal‘trophallactic’pellets– that
is,foodsharedbetweenants
viaregurgitation.Closeand
carefulobservationina captive
situationsometimesrevealsthe
woodlouse‘begging’forthis
foodsourcebyfacinganantand
stimulatingit withitsantennae.
Asfarastheantsare
concerned,thisinquiline(an
animalthatoccupiesthe
livingspaceofanother)
mayprovidea sanitary
service.Byacting
likesome14-legged
chambermaid,it is
likelytohelpkeep
theants’tunnelsand
galleriesclean.
Undoubtedly part of the
fascination is how it gets away
with it. Any other woodlouse
would be at best harried, or at
worst quickly attacked, overcome
and dismembered as food.
But dainty little hoffmanseggii
seems to be able to go about
its business without any of this
hassle and risk. It’s almost as if
it is accepted as an ant itself.
The theory goes that an ant
woodlouse can infiltrate the host
colony by taking on the odour
of the ants, and acquiring the
scent ‘badge’ unique to eachA
ntsarejustabout
everywhereonland.
Theydominateso
manyhabitats–
includingourlawns,allotments,
patiosandpavements– thatthey
representa valuableresourceto
anyanimalabletooutwittheir
impressivearrayofdefencesand
infiltratetheircitadels.Ofthe
ant-loving, or myrmecophilous,
species that develop complex
relationships with these super-
social insects, arguably none is
more beautiful nor more furtive
than the diminutive Platyarthrus
hoffmannseggii or ant woodlouse.
You might think this creature
would be difficult to find, given
it is 5mm long and rarely found
outside ant nests. However,
flip over a flat, sun-warmed
object such as a rock, paving
slab or piece of corrugated
iron (anything that acts as a
natural solar panel and storage
heater) and you’ll often see one
hunkered down among the
ant brood. Its blanched white
complexion contrasts with
the dark soil and ants, yet it’s
unmistakably a woodlouse, just
smaller and paler than you might
be used to.
Being a woodlouse, it feeds
on pretty much anything itNICK
BAKER
N
Hidden
LIVING IN THE DARK
Some species don’t need light to survive.
Like many cave-dwelling species,
from centipedes and shrimps to
salamanders and fish, the ant
woodlouse has forfeited
both colour and eyes.
Deep inside an ant
nest, it doesn’t
need either.
Both pigment
and eyes are
energetically
expensive tomaintain. So, ancestors of
the ant woodlouse, like many
troglodytes, relinquished them to
the darkness. Any advantage
that they might have
provided is negated by
a life in the lightless
galleries of the ant
community. Here,
the primary means
of perception are
smell and touch.Some ant woodlice
have a dark band down
the middle, which is
their gut contents
showing.D I D Y O U
KNOW?ANT WOODLOUSE
Ant woodlice have
the same armoured
symmetry as
other woodlice.