PAUL BERTNER/MINDEN/NATUREPL.COM, FLPA DUSTAWAY/FLICKR, EMANUELE BIGGI/NATUREPL.COM X2Adult moths and their caterpillars are masters
of masquerade. Excrement is just one of a host
of unpalatable things that they replicate, from
dead leaves to lichen, twigs, bark and stone.
Macrocilix maiaof southern Asia recreates
an entire scene: the adult moth’s open wings
suggest not only freshly dribbled bird poo, but
also two visiting flies, complete with wings, legs
and red eyes.
How on Earth does such mind-boggling
trickery evolve? “Birds have better colour vision
than we do,” says Skelhorn, “and they can
make out finer detail. So to fool them, there’s a
strong selection pressure. Over time, you get the
evolution of perfection.” However, he cautions
that there may also be some other trade-off going
on. There’s been little research so far into this
species, and there might be other evolutionary
reasons – apart from deception – for whyM. maia
has developed this impressive wing pattern.
“There are many ways for spiders to look unspidery,” says
Goodacre, but imitating poo is something at which they
excel. Worldwide, several groups of spider are virtuoso faeces
mimics, she says. “They clearly have the genetic architecture
to masquerade.” This subterfuge can involve a suite of physical
adaptations, for example, adopting the size, colour, texture and
patina of bird droppings.
Some species, such as Southeast Asia’sPhrynarachne decipiens
(picture 1, opposite) andP. r ugos a( 2 ) of Africa, heighten the
illusion by giving off the whiff of fresh droppings and weaving a
messy web around themselves. Poo-mimicking spiders also retract
their limbs, changing their silhouette to an amorphous splodge.
As Goodacre says: “Extended legs are a giveaway, but you can fix
this for free.”
The ability of poo-mimicking spiders serves different uses in
different species.Celaenia excavata( 3 ) is a nocturnal moth-hunter,
whose camouflage seems to be a daytime defence from predators
such as birds.Arkys curtulus( 4 ), on the other hand, hunts by day
and appears to use poo mimicry aggressively, to lure dung-loving
flies to their doom.�
STILL LIFE
�SPOOF SPIDERS