An unlikely relationship was found to thrive in the Borneo jungle. One pitcher plant adores its bat tenants for the guano drops they leave behind to feed the plant the nutritious nitrogen.
The pitcher plant is known as Nepenthes hemsleyana, and like other pitcher plants in the jungle is labeled as flesh-eating. Unfairly, as Nepenthes hemsleyana long lost the flesh-eating habits, finding instead a different adaptation mechanism to survive.
With its elongated leaves, shaped to conveniently harbor the insects that would be lured into the deathly traps, nepenthes hemsleyana is untypical compared to its kin.
For all other pitcher plants, the vase-like leaves are reservoirs where enzymes are decomposing the corpses of the insect victims for the nitrogen they contain. But for Nepenthes hemsleyana, this doesn’t hold true.
Ulmar Grafe of the Brunei Darussalam University discovered that the slightly oversized pitcher leaves of the Nepenthes hemsleyana neither release the usual attractant substances, nor do they have the same amount of insect corpses.
Instead, they safely harbor bats. More precisely, Hardwicke’s woolly bats as reported by another two scientists who joined the team, Michael and Caroline Schoner of Greifswald University. Most interesting is that Hardwicke’s woolly bats roost only in the pitchers of Nepenthes hemsleyana.
How did this uncanny relationship develop? Well, for once, guano, the dropping of the woolly bats is rich with the much needed nitrogen that the Nepenthes hemsleyana relies on for survival. Guano provides the pitcher plant with one third of its necessary. And that’s a good deal in the Borneo jungle where nitrogen is scarce in the soil.
Another reason is that the pitcher plant developed into a roomy, cosy space for the woolly bats to roost. A symbiotic relationship between a carnivorous plant and a species of bats that also lowered the enzyme-rich liquid levels in the pitchers of Nepenthes hemsleyana.
The woolly bats and the pitcher plant have developed the relationship also based on echolocation adaptation. How do the woolly bats find precisely Nepenthes hemsleyana in the abundant vegetation and not some other closely resembling carnivorous pitcher plant?
The team commented:
“It started when we were searching for the plants in the forest. We had a lot of difficulty. The vegetation is dense and the pitchers are green”.
For the woolly bats, navigating the green Borneo jungle depends solely on echolocation. Reflecting echoes are the only means to map the surrounding environment. But they are beamed back to the woolly bats from everything around. So how do they recognize specifically Nepenthes Hemsleyana’s safe harbor?
Another scientist joined the team to solve this puzzle. Ralph Simon of Erlangen-Nurnberg University looked into the specific characteristics of the pitcher plant that makes it so recognizable for the woolly bats.
The back wall of the pitcher of Nepenthes hemsleyana is curved, elongated and wide to function as a parabolic dish, comparable to other similar pitcher plants that do not present the same structure.
As the woolly bats map their way through the abundant vegetation, other pitcher plants are dispersing the sounds to the sides instead of beaming them towards the bats.
Thus, while the woolly bat finds a hospitable home, Nepenthes hemsleyana finds a nutritious food source in the bats’ guano.
Image Source: dispatchtimes.com