Beefy Jaws May Help Some Spiders Gather Water

The mega-mawed spider appeared to use the water to reconstitute dried-up food.
A spider carrying a drop of water in its mouth.

Spider species in the group known as long-jawed orb weavers can carry water drops in their mouths.

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Young Swee Ming via Shutterstock

Jude Coleman, Contributor

(Inside Science) -- In the wetlands of Australia, a cheeky spider may have found a way to slurp up extra snacks. Last month in the journal Ethology, researchers reported an instance in which a long-jawed spider in the genus Tetragnatha used its gangly mouthparts to scoop up water and possibly rehydrate its dead, shriveled prey with it, according to author John Gould, a biologist at the University of Newcastle in Australia. 

Gould was on a night field trip on Australia's Kooragang Island, looking for threatened frogs, when he came across a long-jawed orb weaver in its web. He watched the spider descend on a bungee cord of silk to the surface of the pond below. Fetching a water drop between its jaws, the spider zoomed back up its lifeline and deposited the water onto its silk-wrapped prey. 

As their name implies, Tetragnatha have ample jaws that they use for feeding and in mating rituals. The supersized mouthparts enabled the spider to carry its liquid cargo across its web, "almost like carrying water on a plate," Gould wrote in an email. 

He speculates the spider was rehydrating the withered prey carcass to extract more juice from it -- like a packet of dehydrated arachnid backpacking food. This may be a new behavior for spiders, which have been known to gather water from dew drops, but not directly from a water source. 

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Jude is a freelance science journalist and graduate student in the University of California, Santa Cruz Science Communication program. Her work centers around environmental science and ecology.