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Here Are The Animals That Are the Best at Pretending to Be Poop

Moth caterpillars change their posture to look like bird dung, and they’re not alone

Poop or a caterpillar? The giant swallowtail caterpillar is one of a few species that elude birds by pretending to be their poop. (Adam Skowronski/Flickr)
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If it looks like poop…it actually might be a caterpillar. Or a butterfly. Or a spider. In fact, masquerading as poop is a more common technique than you might expect. Here are some of the very best masters of fecal disguise.

Moth caterpillars

Some moth caterpillar species have white and brown coloration that gives them the appearance of a bird dropping. Researchers now report in the July issue Animal Behavior that they take the disguise a step further also change their posture to look like a dollop of excrement when resting on leaves or branches.

For the moth caterpillars, taking on the posture of poop pays off and they are much better able to hide from birds and avoid getting pecked when curled up rather than stretched out, the new study finds. 

Orb-weaving spiders

Found in the forests of Southeast Asia, an orb-weaving species called Cyclosa ginnaga incorporates its web into its disguise for full effect. The spider spins spiral silk decorations and pieces of leaves into its web and positions its brown and white splattered body in the midst to create the illusion of bird poop against a green leafy background. Other orb weavers incorporate spiders, leaf matter and prey carcasses into their web decorations, and its possible that they may be achieving a similar effect.

Giant swallowtail butterflies

In their caterpillar form, giant swallowtail butterflies (Papilio cresphontes) take on a much less pleasing aesthetic than the magestic winged creature they will eventually become. Like the moth caterpillars, they use their black, brown and white coloration to hide from bird predators by resembling poop. Younger caterpillars are generally smaller and more effective at the disguise.

Bird dropping spiders

A few different spider species have garnered the nickname “bird dropping spider,” but Celaenia excavata is perhaps the most well known. Common in the woodlands of eastern and southern Australia, this arachnid curls up and stays extremely still to resemble a ball of dung. To catch prey, however, C. excavata employs a different form of trickery. At night, they produce a chemical that resembles female moth pheromones to attract and eat the males.

Crab spiders

A species of crab spider (Phrynarachne decipiens) has also garnered the nickname bird dung spider. It lives in the tropical environments of Malaysia and Sumatra. The crab spider crouches on leaves and stays extremely still, using both its coloration and posture. To complete the look, it emits an odor not unlike that of bird poo.

About Helen Thompson
Helen Thompson

Helen Thompson writes about science and culture for Smithsonian. She's previously written for NPR, National Geographic News, Nature and others.

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