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The carnivorous plant that uses SONAR to coax bats to roost inside it... so it can eat their POO

Nepenthes hemsleyana plant uses bat droppings as a source of nitrogen
In exchange the bat gets a cosy place to roost safe from parasites
The plant uses acoustic reflectors to attract the bat in a the crowded forest
Adaptation arose as a result of the plant being terrible at catching insects

Published: 08:31 EST, 14 July 2015 | Updated: 08:44 EST, 14 July 2015

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A species of carnivorous plant uses an ingenious trick to coax bats into its clutches.. so it can feast on the flying mammal's poo.

The tropical plant uses an 'acoustic reflector' to bounce the bats' own sonar call signals to attract it in order to retrieve the unusual harvest.

In return the bat is offered a cool and comfy spot to roost in the hot rain forest of Borneo.

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An unusual partnership: The tropical plant Nepenthes hemsleyana uses an 'acoustic reflector' to bounce the bats' own sonar call signals to attract it in order to retrieve the nitrogen from bat droppings

It is thought that the pitcher plant, Nepenthes hemsleyana, digests the bat droppings to use as a source of nitrogen.

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

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

The bizarre discovery was made when study author Ulmar Grafe of the University Brunei Darussalam discovered bats roosting inside pitcher plants.

He, along with Michael and Caroline Schöner and Gerald Kerth, senior author of the new study, first explored what the plants and their bat partners were each getting out of the deal.

Their findings - that the plants offer bats a place to roost in return for nitrogen - helped to explain something that had vexed pitcher plant researchers: Nepenthes hemsleyana are terrible at attracting insects compared to their other carnivorous cousins.

Kerivoula hardwicki bat enters a N. hemsleyana

The researchers wanted to discover how the plants attracted the bats, as both species are relatively rare and live in crowded forests.

There are some flowers that have a similar problem - they depend on nectar-feeding bats to pollinate them, and have adapted a reflector in the form of dish-shaped petals to guide the bats towards them using their own call.

THE SECRET OF THE POO PLANT

The bizarre discovery was made when study author Ulmar Grafe of the University Brunei Darussalam discovered bats roosting inside pitcher plants.

He, along with Michael and Caroline Schöner and Gerald Kerth, senior author of the new study, first explored what the plants and their bat partners were each getting out of the deal.

Their findings - that the plants offer bats a place to roost in return for nitrogen - helped to explain something that had vexed pitcher plant researchers: those plants, Nepenthes hemsleyana, are terrible at attracting insects compared to their other carnivorous cousins.

They found that the plants had adapted acoustic reflectors to bounce back the bats' own call.

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

It now appears that the unrelated pitcher plant N. hemsleyana does the same thing, but for a different reason.

The researchers recruited Ralph Simon from the University of Erlangen-Nuremberg to their team. Simon had been studying the acoustic adaptations of bat-pollinated flowers for some time.

In Borneo, Simon and his colleagues used an artificial biomimetic bat head that emits and records ultrasounds to test the pitchers' acoustic reflectivity from different positions and angles.

Those studies uncovered a strong echo reflection from the pitchers' back walls, where the plant form works perfectly as an effective reflector.

'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,' Schöner said.

'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.'