Weird Nature: The Pitcher Plant Rat Toilet
As a young lad, I let my imagination rip while reading The Lost World by Sir Arthur Conan Doyle, who is better known for his Sherlock Holmes novels. Conan Doyle’s Lost World is set in the Amazon. The main character, Professor Challenger and his team climb to the top of a mountain so inaccessible that no one has been there before them. Once on the plateau, they discover a world where nature has been left behind in prehistoric times, with dinosaurs and other extinct species roaming around in Conan Doyle’s own 1912 version of Jurassic Park. I always wondered if such a place might truly exist — not on the scale of the Lost World plateau, but perhaps a little pocket somewhere with strange relics living on from pre-history. Now I realize there is enough weird stuff out in the wild to satisfy any cravings for the exotic and one plant epitomizes that perfectly. Of all the mysteries in the natural world, none is more bizarre than Nepenthes lowii, a jungle dwelling denizen of Borneo.
N.lowii is a pitcher plant and, like all of its kind, it kills for a living. Pitcher plants are basically elaborate insect traps. Bugs are lured to their deaths by the nectar-like substance produced in the top of the plant. Some get a good, free feed and escape unharmed, but others will fall or slip into the trap below — the pitcher itself. The large receptacle from which the plant gets its name is filled with a fluid that contains invisible elastic threads that entangle the prey and prevent the insect from escaping. The pitcher, in effect, becomes a big bowl of insect soup, as its enzymes break down the bugs into digestible slurry. The great reward for the plant is nitrogen, which is deficient in its natural habitat.
So far so gross, but what’s so special about N.lowii? One species of pitcher plants — Nepenthes rajah, the largest of all carnivorous plants — was rumored to feed on much more substantial prey in the form of rats. This is the stuff of nightmares and weird enough to find a place in any imaginary “Lost World.” But when ecologists began to study them, the largest Nepenthes revealed something totally unexpected. Intrigued by the fact that some pitcher plants had bowls that were much bigger and stronger than would be necessary just to trap insects, the scientists started to watch them and even set up cameras to record them remotely. They soon discovered that N.lowii had a regular visitor, a small rat-like creature — the Borneo mountain tree shrew, Tupaia montana. Just like the insects, the shrews were tempted by the delicious, sweet nectar. But, being much larger, they don’t get trapped. They can lick away to their heart’s content. Just to show their gratitude, they leave a little thank you gift, as they carefully excrete the contents of their bowels into the pitcher. The shrew gets its sugar fix and of course the plant gets its nitrogen top-up. It was all caught on video.
The Borneo plant carnivore is not a rat-catcher. It’s a super-efficient animal toilet and recycling facility.
If that’s not cool, I don’t know what is.
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