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Carnivorous plants communicate with bats

Clever plant A large, meat-eating pitcher plant in Borneo has evolved a unique way to communicate with bats that it hopes to attract.

The plant, Nepenthes hemsleyana, communicates via special structures that reflect the bats' ultrasonic calls right back to the flying mammals, according to a study published in the latest issue of the journal Current Biology .

"With these structures, the plants are able to acoustically stand out from their environments so that bats can easily find them," says co-author Michael Schöner of Ernst-Moritz-Arndt-University of Greifswald.

"Moreover," he continues, "the bats are clearly able to distinguish their plant partner from other plants that are similar in shape, but lack the conspicuous reflector."

Schöner, senior author Gerald Kerth, and their colleagues determined that the bats defecate in and around the plants, keeping the latter well fertilised with their droppings.

Once the bats find the plants, they settle in towards the top — away from the plant's deadly digestive liquids — and enjoy a cool place to roost.

The seemingly clever plants get something out of the deal too.

It was that discovery that led to the study on the ultrasound communication in the first place, as the researchers wondered how the carnivorous plants were so successful at grabbing the attention of bats flying by.

Suspecting that echolocation was involved, the scientists used an artificial biomimetic bat head that emits and records ultrasounds to test the pitcher plant's acoustic reflectivity from different positions and angles.

The experiments uncovered a strong echo reflection from the plant's back walls, where the shape works perfectly as an effective reflector.

Subsequent behavioural experiments showed that the bats respond to those sounds echoed back to them from the plants.

Bats were better at finding partially hidden pitcher plants when their reflectors were intact than when the reflector had been reduced.

The bats also chose pitcher plants more often as the best places to roost when the reflector had not been reduced.

The study answers a longstanding question about these particular plants: Why don't they feast on many insects versus what other pitcher plants do?

As it turns out, they don't have to, given all of the nutrient-rich bat poo nearby.

The study further adds to the growing body of research showing that plants can solve complex problems without having a brain.

"Carnivorous plants in general have already solved the problem of nutrient deficiency in a very unusual way by reversing the 'normal system' of animals feeding on plants," says Schöner .

"It is even more astonishing that in the case of N. Hemsleyana the system is taking a new turn.

"While N. Hemsleyana reduced many insect-attracting traits, it obviously exhibits some traits that are highly attractive for a species that provides the plants with nutrients without being digested by the plant itself."

Related: Pitcher plant's tricky trap pulls in the ants

This article originally appeared on DiscoveryNews.com