วันอังคารที่ 28 มกราคม พ.ศ. 2557


 
Humans aren’t the only animals that build intricate homes and other structures: The animal kingdom abounds with talented architects. 
From dams to nests to body armor, these feats of animal ingenuity will blow your mind—and perhaps inspire you to get up off that couch.
Beavers
Beavers might be the most well-known animal architects, and with good reason. These prolific builders fell trees and gather sticks and mud to construct dams, which create ponds that offer predator protection and easy access to food during the winter.
A picture of a beaver.
A beaver drags a log at a pond in Denali National Park and Preserve in Alaska. Photograph by Alaska Stock, Alamy
Beaver families live in lodges within the dams, and are constantly “busy as beavers” adding to and repairing the structures, says the Washington Department of Fish and Wildlife.
Although the average beaver dam is about 6 feet (1.8 meters) high and 5 feet (1.5 meters) wide, they can be much bigger. In 2007, experts spotted the world’s largest beaver dam in Alberta, Canada, using Google Earth.
The dam, located on the southern edge of Wood Buffalo National Park, stretches for an amazing 2,788 feet (850 meters). Biologists estimate the dam took 20 years to build.
Cathedral Termites
Australia‘s Northwest Territory is dotted with the spectacular structures of cathedral termites, which build mounds that can tower more than 15 feet (4.6 meters) high. Constructed from mud, chewed wood, and termite saliva and feces, each mound is a self-sustaining termite mega-city. (See your pictures of impressive architecture.)
A picture of a cathedral termite mound
A cathedral termite mound in Australia. Photograph by Jason Edwards, National Geographic
The insects build their mounds facing north to south to regulate heat, and internal tunnels serve as ducts to circulate air from the cooler soil at the base of the mound to the warmer top. According to University of Maryland entomologist Michael Raupp, It’s a natural version of air-conditioning that keeps the colony cool even as temperatures outside rise to scorching hot.
Underground, the termite colony can spread out over several acres. Water collects as condensation in the cool interior of the mound, where some termites even maintain underground fungi gardens that they cultivate with plant matter and use to feed the bustling termite metropolis.
Sociable Weaver Birds
If you’re ever in southern Africa and see something that looks like a huge haystack stuck up in a tree, you’ve probably found a sociable weaver nest. Sociable weavers build the biggest nests of any bird, housing up to 400 individuals. Some nests can remain occupied for over a hundred years.
A picture of a sociable weaver (Philetairus socius) with grass in its beak for building its nest, Etosha National Park, Namibia, Africa
A sociable weaver carries nest material in Namibia’s Etosha National Park. Photograph by Imagebroker, Alamy
According to the San Diego Zoo, a nest consists of separate chambers, each of which is occupied by a breeding pair of birds. Sociable weavers use large sticks to create the roof and basic structure of the nest and dry grasses to form the individual chambers, which are lined with softer grasses and fibers. They even install a security system: Sharp, spiky straw protects the entrance tunnels from predators. (Also see “Fish ‘Engineers’ Dig Up Homes for Marine Life.”)
The inner chambers retain heat and are used at night, while the outer rooms are cooler and used for daytime shade. Sociable weaver nests are so sturdy and comfortable that other birds are known to move in and share the cozy space.
Paper Wasps
Wasps invented paper long before the first human thought to put his thoughts down on a sheet of papyrus.
Paper Wasp Polistes sp adult on nest under Palm Frond Rio Grande Valley, Texas.
A paper wasp clings to its nest in Texas’s Rio Grande Valley. Photograph by Rolf Nussbaumer Photography, Alamy
Texas A & M University entomologists say paper wasps gather bits of wood and plant fiber and chew them into a soft pulp. They choose a nest site, such as a tree branch or behind a window shutter, and spit out their pulp to construct a nest. As the pulp dries, the paper hardens and eventually grows into a complex, water-resistant home. (Watch a video on what makes a good architect.)
The nest is made up of hexagonal cells in which the young will develop, and many of them also have a paper envelope covering them for protection against parasites. As the colony grows in number, so too does the nest, with new generations of workers building new cells as needed. Mature nests contain up to 200 cells.
Over the winter, paper wasp nests fall apart, so a new one must be constructed each spring. Mated queens spend the cold months hibernating and awaken each spring to find a suitable nesting site and begin the construction process anew.
Caddisfly Larvae
Caddisflies are small, mothlike insects, but it is in their larval stage that they prove their prowess as architects.
Caddisfly larva inside its protective case
Caddisfly larva seen inside its protective case. Photograph by MShieldsPhotos, Alamy
According to North Carolina State University, all caddisfly larvae are aquatic, and some of them live within protective cases that they build from their own silk and whatever materials they find lying around, usually gravel, twigs, leaf fragments, and other debris. (Read more about caddisflies in National Geographic’s Water Currents blog.)
Nests of caddisfly larvae on stream bottom
A nest of caddisfly larvae sits on a stream bottom. Photograph by John T. Fowler, Alamy
Caddisfly larvae will scavenge for building materials from whatever is available in their environment. In the early 1980s, French artist Hubert Duprat decided to take advantage of the caddisfly larvae’s urge to build by providing them with precious materials like gold flakes, opals, pearls, and turquoise. The caddisflies obliged by constructing beautiful—and expensive—cases that are also works of art.

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