Sloths – Industrial Ecology

What Can Sloths Teach Us About Energy Efficiency?

It’s a scientific fact that there’s nothing cuter than a baby sloth in a bucket. Sloths have an outstanding survival strategy, as their unexpectedly high density in South and Central American tropical forests attests. In some areas, sloths consume half the energy and make up two-thirds of mammalian biomass. That’s a lot of sloths. But it’s hard to see them because they hardly move—their leafy diets just don’t provide enough energy for them to monkey around. How do they succeed on such meager rations? Simple. They are consummate energy misers. Can humans learn something about conserving energy from the sloth?

The sloth spends his whole life browsing in the trees, and he’s built perfectly for it. In fact, he can’t even stand up on the ground because his hands and feet are essentially coat-hangers. He is designed to do one thing: hang upside-down from a horizontal tree branch. His body is designed to resist tension forces, not compression. He’s a great natural model for hanging roofs, gardens, and bridges.

Application

Industrial ecology has been defined as a “systems-based, multidisciplinary discourse that seeks to understand emergent behaviour of complex integrated human/natural systems”. The field approaches issues of sustainability by examining problems from multiple perspectives, usually involving aspects of sociology, the environment, economy and technology. The name comes from the idea that we should use the analogy of natural systems as an aid in understanding how to design sustainable industrial systems.

The Kalundborg Industrial Ecosystem in Denmark, where a power plant, oil refinery, pharmaceutical plant, plasterboard factory, an enzyme manufacturer, a waste company and the city all trade and share byproducts and heat emissions. Why shouldn’t our human industrial ecosystem be more sloth-like, with one species’ waste becoming food for another, reducing raw materials, pollution, and waste? It’s another great idea from Mother Nature. Just like baby sloths in a bucket.

Sloths’ fur provides a feast for hungry birds

For instance, each individual hair on a sloth has a special groove which absorbs water like a sponge. Certain blue-green algae love this. They multiply in the rainy season, turning the sloth a nice shade of green, perfectly hiding him from hungry harpy eagles. The sloth licks the algae for a nutrient boost—like a hippie with a shot of wheatgrass—and even absorbs it through the skin. The algae is passed directly from mom to baby sloth, and each species of algae is only found on a unique population of sloths. In fact, most organisms living on any given sloth species have been evolving separately just as long as the sloths themselves have, about 20 million years. These are a pretty specialized bunch of critters. For example, the sloth moth only lays its eggs in sloth dung. Since a sloth spends most of its life in one single tree, he feels compelled to descend once a week to dig a hole and carefully fertilize it. The moth takes this opportunity to jump off and lay her eggs, then jump back on for the ride up the tree. The eggs hatch, the caterpillars metamorphosize, and the new moths fly off to find new sloths.
While the three-toed sloth dines on leaves, other animals dine on the sloth. The sloth’s fur is chock-full of moths (as well as other insects, algae, and fungi), which spend much of their lives on its back—using it like a matchmaking service to help them find mates, and laying their eggs in the sloth’s poop, which nourishes their larvae. Now scientists report this month in Frontiers in Ecology and the Environment that hungry brown jays feast on this moving buffet of insects (as seen in this video). But is the brown jay friend or foe of the sloth? That depends on whether the tree-dwelling mammals benefit from their moth companions or merely tolerate them. Recent research suggests that sloths are gardeners, cultivating and eating the algae on their fur for the purpose of supplementing their diets. In that case, the moths are an essential player, as they act like fertilizer—when they die, the algae consume the nutrients in their remains. So sloths might be wise to bat away the moth-eating birds, if they can stand to lift a lethargic limb.

One of the central principles of Industrial Ecology is the view that societal and technological systems are bounded within the biosphere, and do not exist outside of it. Ecology is used as a metaphor due to the observation that natural systems reuse materials and have a largely closed loop cycling of nutrients. Industrial Ecology approaches problems with the hypothesis that by using similar principles as natural systems, industrial systems can be improved to reduce their impact on the natural environment as well.

The sloth is the world’s slowest mammal, so sedentary that algae grows on its furry coat. The plant gives it a greenish tint that is useful camouflage in the trees of its Central and South American rain forest home.

Sloths are identified by the number of long, prominent claws that they have on each front foot. There are both two-toed and three-toed sloths.

All sloths are built for life in the treetops. They spend nearly all of their time aloft, hanging from branches with a powerful grip aided by their long claws. (Dead sloths have been known to retain their grip and remain suspended from a branch.) Sloths even sleep in trees, and they sleep a lot—some 15 to 20 hours every day. Even when awake they often remain motionless. At night they eat leaves, shoots, and fruit from the trees and get almost all of their water from juicy plants.

Sloths mate and give birth while hanging in the trees. Three-toed sloth babies are often seen clinging to their mothers—they travel by hanging on to them for the first nine months of their lives.

On land, sloths’ weak hind legs provide no power and their long claws are a hindrance. They must dig into the earth with their front claws and use their strong front legs to pull themselves along, dragging their bellies across the ground. If caught on land, these animals have no chance to evade predators, such as big cats, and must try to defend themselves by clawing and biting.

Though they couldn’t be clumsier on land, sloths are surprisingly good swimmers. They sometimes fall directly from rain forest trees into rivers and stroke efficiently with their long arms. The three-toed sloth emits a long, high-pitched call that echoes through the forests as “ahh-eeee.” Because of this cry these sloths are sometimes called ais (pronounced “eyes”). Three-toed sloths also have an advantage that few other mammals possess: They have extra neck vertebrae that allows them to turn their heads some 270 degrees.

The Kalundborg industrial park is located in Denmark.

This industrial park is special because companies reuse each other’s waste . For example, the Energy E2 Asnæs Power Station produces gypsum as a by-product of the electricity generation process; this gypsum becomes a resource for the BPB Gyproc A/S which produces plasterboards. This is one example of a system inspired by the biosphere-technosphere metaphor: in ecosystems, the waste from one organism is used as inputs to other organisms; in industrial systems, waste from a company is used as a resource by others.

Apart from the direct benefit of incorporating waste into the loop, the use of an eco-industrial park can be a means of making renewable energy generating plants, like Solar PV, more economical and environmentally friendly. In essence, this assists the growth of the renewable energy industry and the environmental benefits that come with replacing fossil-fuels.

IE examines societal issues and their relationship with both technical systems and the environment. Through this holistic view , IE recognizes that solving problems must involve understanding the connections that exist between these systems, various aspects cannot be viewed in isolation. Often changes in one part of the overall system can propagate and cause changes in another part. Thus, you can only understand a problem if you look at its parts in relation to the whole. Based on this framework, IE looks at environmental issues with a systems thinking approach.

Take a city for instance. A city can be divided into commercial areas, residential areas, offices, services, infrastructures, etc. These are all sub-systems of the ‘big city’ system. Problems can emerge in one sub-system, but the solution has to be global. Let’s say the price of housing is rising dramatically because there is too high a demand for housing. One solution would be to build new houses, but this will lead to more people living in the city, leading to the need of more infrastructure like roads, schools, more supermarkets, etc. This system is a simplified interpretation of reality whose behaviors can be ‘predicted’.

The Kalundborg industrial park

In many cases, the systems IE deals with are complex systems. Complexity makes it difficult to understand the behavior of the system and may lead to rebound effects. Due to unforeseen behavioral change of users or consumers, a measure taken to improve environmental performance does not lead to any improvement or may even worsen the situation. For instance, in big cities, traffic can become problematic. Let’s imagine the government wants to reduce air pollution and makes a policy stating that only cars with an even license plate number can drive on Tuesdays and Thursdays. Odd license plate numbers can drive on Wednesdays and Fridays. Finally, the other days, both cars are allowed on the roads. The first effect could be that people buy a second car, with a specific demand for license plate numbers, so they can drive every day. The rebound effect is that, the days when all cars are allowed to drive, some inhabitants now use both cars (whereas they only had one car to use before the policy). The policy did obviously not lead to environmental improvement but even made air pollution worse.