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What is a bird-dropping spider? © Shutterstock

What is a bird-dropping spider?

Published: 09th March, 2022 at 04:00
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When is the comment, "you look like ****" a compliment?! When you’re a bird-dropping spider.

In ordinary circumstances, it’s not good to look like a pile of poo, but for the bird-dropping spider, Celaenia excavata, this evolutionary strategy is a lifesaver.

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Found in Australia and New Zealand, the medium-sized arachnid has a chunky, triangular body daubed in splodges of brown, black and white. During the day, when it rests, it folds its legs up against its body, making it appear, to all the world, like a freshly deposited bird dropping. This camouflage is so convincing that birds often overlook this potential food source, leaving the faecal fraudster to brazenly style it out on the surface of a leaf or twig.

After sunset, however, the bird-dropping spider takes its mimicry skills to another level to help it catch its prey. The spider dangles upside-down from a tree with its front legs outstretched and releases a chemical scent that mimics the airborne sex pheromone emitted by female lawn armyworm moths to attract mates.

Hapless male moths looking for love fly towards the rogue odour and are then grabbed by the spider and devoured, or wrapped in silk and saved for later.

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Authors

Helen Pilcher
Helen PilcherScience writer, presenter and performer.

Helen Pilcher is a tea-drinking, biscuit-nibbling science and comedy writer, with a PhD in cell biology.

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