Weird Animals – the Tree Shrew and its Poo

No, I am not referring to the shrew in Shakespeare’s “Taming of the Shrew.” That shrew referred to a shrill, scolding woman. This shrew is a tree shrew, a small mammal that lives in the mountains of Borneo.

You won’t believe what I am about to tell you about the relationship between the tree shrew’s poo and the Giant Montane Pitcher plant.

If you have read my “Weird Animals – the Dung Beetle,” you are aware of the proclivities of this ingenious beetle.

It discovers and transports the dung of large animals for both its home and its sustenance. But the tree shrew takes its poo to a whole ‘nother level.

You are probably already aware of my supernatural ability to converse with animals. But now I have also mastered the tremendous talent of telepathic transportation. So here I am in the mountains of Borneo in Southeast Asia looking for a voluble tree shrew to interview. Aha – there is a likely specimen.

Borneo, located southwest of the Philippines, is the third largest island in the world (287,000 square miles) and the largest island of Asia. It is divided into regions governed by Indonesia, Malaysia and Brunei.

me – Good morning, Mr. Tree Shrew. Do you have a few moments for an interview?

Tree Shrew – If you will publish my photo – I’m unattached currently and seeking companionship – I’ll be happy to oblige you. And it’s Ms. Tree Shrew. You can call me Treesha.

me – Thank you, Treesha. Are there many more tree shrews like you?

Treesha – Actually, about 19 species altogether (of the family Tupaia).

me – I was very surprised, Treesha, to learn that scientific studies now indicate that tree shrews are more closely related to primates than to rodents.

Treesha – That is absolutely correct. We also have the highest brain to body mass ratio of any mammal including humans.

me – You know, you resemble somewhat a squirrel, or even a cute half-pound mouse. No offense.

Treesha – None taken. I hear that all the time. But we do not have whiskers and we do not eat nuts – we eat insects, small lizards and fruit. We have tiny sharp claws on our hands and feet for grasping trees (like monkeys).

We also have a pair of extra tongues beneath our main tongue. These are also found in lemurs – the primates that evolved before monkeys and apes.

Did you know that we are diurnal – active during daylight, with an internal temperature close to the 98.6 degrees that is normal for humans? To maintain that temperature and our active lifestyle, we must eat our average body weight in food each day.

me – Which is … ?

Treesha – … about seven and a half ounces – the size of one McDonald’s Big Mac.

me – (astounded) How do you know about the Big Mac?

Treesha – I once ate one lost by a mountain hiker. Couldn’t eat another drop of food for the rest of the day.

me – What about housekeeping? Does your male counterpart chip in?

Treesha – Our mates are well trained. They construct two separate nests – one for Mom and Dad and one for the tiny offspring. They build the nests in trees, under roots, or in hollow bamboo and fill them with dry leaves.

When I have babies (up to three), I will visit them every two days to nurse for ten to fifteen minutes. That’s it. They are on their own after one month.

me - Let’s digress for a moment and discuss the evolution of the Giant Montane Pitcher Plant before we get to the Poo Connection. Pitcher plants are the largest carnivorous plants, and the largest specimens are found right here in the mountains of Borneo.

Treesha – That’s true. The plant known as Nepenthes rajah is believed to be the largest meat-eating plant in the world. It grows a pitcher that can hold over two quarts of water if filled to the brim.

me – I know that nitrogen is a very important element for plants. But although the atmosphere contains vast quantities of nitrogen, plants cannot absorb it directly from the air.

Treesha – Exactly! They get it through their roots after oxygen atoms have been added to form nitrates. The pitcher plants then metabolize through a process known as the nitrogen cycle.

me – But tropical soils are notoriously lacking in this substance – they can’t recycle nitrates from decaying leaves as in more temperate climates. One of the reasons why farmers rely on so much fertilizer to supplement the soil.

Treesha – You seem to be so knowledgeable. Do you have a degree in Agriculture?

me – No, I have a B.A.H. – Bachelors in Animal Husbandry. Sorry, the debbil made me do it.

Treesha – I understand. If I had attended college it would have been to attain my M.R.S.

me – Touche! So how do these pitcher plants obtain nitrogen?

Treesha – Wait ‘til you hear this. The colors of the pitcher plants are arranged to attract insects. They broadcast wavelengths that can be seen like lighthouse beacons. The insects provide the plant with vital nitrogen and phosphorus, which it cannot obtain any other way.

me – How?

Treesha – When insects land on pitcher plants, they cannot adhere to the surface. They slip and slide into a pool of digestive enzymes where they drown and are ingested by the plant.

Mt. Kinabalu (4095m) is one of the tallest mountains in South-East Asia and is situated in the Kinabalu National Park in the province of Sabah, Malaysian Borneo.

me – So what is this poo connection between the tree shrew and the carnivorous pitcher plant?

Treesha – Here on Mt. Kinabalu insect prey is scarce. The largest meat-eating aerial plant in the world has been designed not to eat small animals like tree shrews or rodents, but small animal poo (feces).

me – Are you saying that the Giant Montane Pitcher Plant on Mt. Kinabalu, Borneo has evolved into a toilet for the tree shrew? A shrew loo?

Treesha – Exactly! Botanists have discovered that this giant pitcher plant has a pitcher the exact same size as a tree shrew's body. The plant uses tasty nectar to attract tree shrews, and then ensures its pitcher is big enough to collect the feeding mammal's droppings.

me – C’mon, are you putting me on?

Treesha – I swear this is true. Picture this scenario. A small tree shrew climbs up to lick the concave lid of the, shall we say, ‘toilet plant.’ The inside of this lid is covered with glands that exude huge amounts of nectar. Busily engaged in slurping down the delicious, sweet nectar that lines the plant’s ‘lid,’ the tree shrew does his or her business in the bowl of the pitcher plant.

Great symbiosis. A sweet, liquid free lunch for the tree shrew and a nice, although some might say ‘crappy,’ deposit for the plant which likely supplies the majority of nitrogen required.

Here’s the video with the proof.

Treesha – Now here’s the clincher. The distance from the front of the pitcher's mouth to the glands on the lid corresponds exactly to the head to body length of the mountain tree shrew.

For the tree shrews to reach the sweet nectar, they must climb onto the pitcher and perch in such a way that their backsides are located over the mouth of the pitcher. Then they do what they gotta do and defecate to mark their feeding territory. Before they leave, they usually mark the plants with their scent by rubbing their genitals onto the lid.

me – (doubtful) But ground-lying, terrestrial pitcher plants have slippery rims to trap insects.

Treesha – That’s what is so amazing. The rim of the aerial type of Giant Montane Pitcher Plant has been modified so that it is not slippery like the insect-trapping varieties. That way, tree shrews stay safe from a spill while eating and pooping.

me – What prevents the tree shrew from, you’ll pardon the expression, missing the hole, so to speak?

Treesha – There's no way for that to happen. The shape of the pitcher opening and orientation of the leaf lid, coated with nectar, ensure that a tree shrew will have to straddle the plant. Ergo, the animal is in the perfect position to take a bathroom break while feeding.

me – And when it rains, the poop will be washed into the bottom of the plant pitcher. What an extraordinary example of plant/animal specialization.

Thank you, Treesha, for enlarging my environmental education. Would you like me to bring you a dozen Big Macs when I return next year?

Treesha – No thanks, I’m watching my diet. But a mini iPad would come in handy! (laughs hysterically)

There is one species of carpenter ant, Campanotus schmitzi, that dives into the terrestrial pitcher-plant digestive fluid and retrieves drowned insects and mosquito larvae for its food. These ants can actually swim and remain submerged for up to 30 seconds! Although it may take them up to 12 hours to haul up their catch.

Sources:

Chin, L., J. A. Moran, and C. Clarke. 2010. “Trap geometry in the giant montane pitcher plant species from Borneo is a function of tree shrew body size.”

Clarke, C. M., U. Bauer, C. C. Lee, A. A. Tuen, K. Rembold, and J. A. Moran. 2009. “Tree shrew lavatories: a novel nitrogen sequestration strategy in a tropical pitcher plant.”

Moran, Jonathan A. 2012.”Tuning of color contrast signals to visual sensitivity maxima of tree shrews by three Bornean highlands Nepenthes species.”

© Copyright BJ Rakow, Ph.D. 2013. All rights reserved. Author, "Much of What You Know about Job Search Just Ain't So."

Learn to write a dynamic resume and cover letter, network effectively, interview confidently, and negotiate salary.