What Animals Reshape Earth's Waterways?

ecosystem engineers. These are organisms that either directly or indirectly alter their physical surroundings in ways that have major impacts on the livelihood of other organisms. Take, for example, the American alligator. Out in the wild, these big reptiles like to make their own swimming pools. Using their snouts and claws, they create massive trend known as gator holes in the limestone around Florida's Everglades. In short order, they flood with water.

They also tend to remain full of water even well into the dry season, a time when standing water can be scarce for other life forms. A gator hole can provide a badly needed oasis of frogs and turtles move into these convenient little ponds while plants around their rims, attracting all kinds of insects. So, as unlikely as it may sound, Florida alligators are environmental stewards. They create brand new homes for their neighbors and in the process, strengthen

the biodiversity of the everglades. Other ecosystem engineers leave different marks. Today, we're looking at a few that reshape rivers, link ponds together, and transform mangrove creeks. Map makers of the world. You'll want to keep your erasers handy when these beasties come to town. First up beavers. The term busy as a beaver really should be considered high. Beavers are hard working rodents. A lone one can cut down up to two hundred trees

in a single year. Famously, they build sturdy homes or lodges for themselves out of branches, mud, and other materials. They can also make their own large scale ponds by damming streams, and this works by creating a backlog of water upstream of the dam. The resulting pond not only gives beavers a place to build their lodge, it also affords easy access to surrounding trees. Often around a foot or a third of a meter, of water covers the bases of nearby pines and hardwoods that once stood on

dry ground. As a result, beavers can swim right up to these trees. They also like to dig canals that branch out of the new ponds, penetrating deep into the local forest. These new wetlands provide homes for smaller animals like amphibians. Plus, the dams make great natural filters, a blocking excess nitrogen from our creeks and streams. However, all of the side effects are positive. When a beaver dam fails, it's liable to flood towns or farms. The aftermath can

be expensive. In the southeastern US alone, these floods are responsible for an estimated twenty two million dollars a year in damages to the timber industry. It's not surprising, then, that many people view beavers as pests. If you have a beaver problem, do know that humane solutions are out there. Next up the adorable yet terrifying hippopotamus. Put a group of hippos and a floodplain with lots of nice, soft soil,

and they'll start reconfiguring the turf. That's because hippos have unique skin that needs to be kept wet for most of the day or they'll become dehydrated, so they plow through the reed beds that ring rivers and lakes, creating deep wallows of water and mud that keep them cool during hot days. They're too heavy to float or swim, so they reshape the soil bed beneath the water to

walk along it, the tops of their heads poking out. However, these wallows don't offer much in the way of food, so at night hippos leave their comfy wallows to go grazing on dry land, returning before the sun. That daily coming and going creates deep depressions in the soil near bodies of water, which in turn become channels worn down over time. These footpaths can be as much as sixteen feet that's five meters wide, and just like gator holes,

they're quick to fill up with water. Oh what's more, hippo highways linking ponds and streams to big rivers can also be established. If the area should flood, these connection points may become an outlet for surging water. They also enable swamplands to expand and under the right circumstances, The trench like trails can divert a great deal of sediment from rivers into ponds. And that's not all that hippos

are doing as they go about their business. Pun intended fifteen analysis determined that hippo dung is an important source of nutrition for at least some of the fish and insects that share the animal's native range. Never underestimate the power of poop. However, for their size, hippos don't actually eat a lot, only about one to one and a

half percent of their body weight every day. Large cattle eat more like two and a half percent, and African elephants can eat over four percent, which is no joke when you weigh some seven tons. On a typical day, an adult elephant will spend twelve to eighteen hours eating, which is vital to the ecosystem. Elephant dung is a nutritious fertilizer for the soils of Africa. It's also a

vehicle by which many seeds are dispersed. Furthermore, by knocking down trees and eating shrubs, these colossal animals convert forests into grasslands, and a two thousand and nine study published in the journal Bioscience revealed even more about the transformative powers that African elephants have over their habitats. Sort of similar to hippos, Elephants are great at building water channels.

The test herbivores cover the same land routes over and over again as they go about finding food and water, making trails in the process. Sometimes multiple generations of elephants will reuse the exact same footpaths. As time goes by, the animals compress the soil, turning their walkways into trenches, and when elephants move back and forth between bodies of water, their sunken trails become nice conduits. Thus, rivers or ponds that were once isolated can be merged via elephant made canals,

providing inroads for other wildlife to travel. And another study of Asian elephant trails in Thailand found that these paths can divert monsoon run off into local streams, preventing flooding. But enough of mammals and reptiles. A number of crustaceans are great diggers, including fiddler crabs, which shelter in tunnels measuring up to three feet or more in that's about

a meter. The holes are quite a construction project. Given the fact that most fiddler species are less than two inches or five centimeters wide, then there are the various species of burrowing crabs of the mangrove swamps and salt marshes of the world. The tunnels that these small crabs build are liable to weaken the surrounding turf. On mangrove swamp shorelines, this has the effect of widening tidal creeks, whose mud and clay based banks are rendered more vulnerable

to erosion by the digging invertebrates. They may also play a key role in aerating the marshy soil and kicking up nutrients from the beds, and that's just part of the story. Because burrowing crabs have such a profound effect on sediment composition, their tunnels can also cause completely new creeks to form within these mangrove systems, and all of this further impacts the plants and other animals that live

around those environments. Those tiny crabs change how microorganisms in places can grow, which changes what foragers and predators come to the area. Just another example of how small actions can add up to huge effects. Today's episode is based on the article Eco engineers five animals that can reshape Earth's waterways on how stuffworks dot Com. Written by Mark Vancini. Brain Stuff is production by Heart Radio in partnership with how stuffworks dot Com and is produced by Tyler Klang.

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