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Friday, January 28, 2011

Carnivorous Plant Lures Bats to Feed on Their Guano

by David DeFranza
nepenthes rafflesiana pitcher plant photo
The plant in question: Nepenthes rafflesiana. Photo credit: Wikimedia Commons

Carnivorous plants tend to make their homes in peat bogs and heaths—environments that have notoriously nutrient-deficient soils. They deal with these deficiencies by trapping insects, lizards, and even small mammals, absorbing nitrogen and other nutrients from their prey as they are slowly digested inside the plant.
For one pitcher plant however, survival is less dependent on snaring unsuspecting prey than it is on making a cozy home for a particular species of bat.

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According to recent research, Nepenthes rafflesiana—native to Borneo, Sumatra, Malaysia, and Singapore—has adopted several unique adaptations that makes it less apt at catching insects and more hospitable for roosting Hardwicke's woolly bats.

Typical pitcher plants have a conical shape and interior walls coated in a slippery liquid. When curious prey wanders into the pitcher's mouth, they begin to slide to the bottom, where a pool of digestive liquid drowns them and slowly breaks down the carcass.

Nepenthes rafflesiana has considerably less slippery liquid and a more shallow pool at the bottom of its pitcher. In addition to this, it has a girdle, mid-way down, the helps keep bats from slipping to the bottom. This makes it easy for bats—which sometimes roost as whole families in one plant—to make their home in the pitcher, a container that provides parasite-free protection from the bat's predators.

READ MORE: The Training of the Shrew: Pitcher Plant Evolves Into Toilet 

In exchange, the bats provide nutrients for the plant, delivered in the form of nitrogen-rich guano dropped down the pitcher.

It's only the second known instance in which a carnivorous plant has developed a mutualistic relationship with a mammal species.