Meet a stream-dweller

Beavers. Pudgy and bucktoothed, with broad, paddle-like tails, are a classic icon of the Canadian Wilderness, and can be found around waterways across north America.

 

You likely know of beavers as the lumberjacks of the natural world. You might wonder, though, how these animals keep their teeth from wearing down with all that wood chewing? The large teeth of a beaver consists of a layer of orange enamel in the front, with the inner surface (facing inside of the mouth) made up of softer dentin. During the chewing of wood, the inner dentin layer wears away much faster that the dentin, which remains largely intact. This means that the bottom edge of these overhanging teeth remains sharp for continuing to harvest wood.

 

Beavers are also well known is their semi-aquatic lifestyle and swimming abilities.  On land, beavers are unable to move very quickly, which makes them vulnerable to predators, such as bears and wolverines. By seeking refuge in the water, and by building wood-based dams as shelter, the beaver remains much safer from predation. Spending much of their time in the water, beavers have a number of useful adaptations for aquatic life. The shape of the beaver’s tail works like a rudder, allowing the beaver to steer itself as it swims. The beaver has webbed feet, like a duck, which also help with swimming. The beaver has oil-producing glands just beneath its fur and, during grooming, spread this oil across their fur to make the fur more water-resistant.

 

Beavers are considered both ecosystem engineers, an animal whose actions can create large scale effects on the landscape around them, and a keystone species: a single species having an exceptionally large impact and importance within its local ecosystem. By gnawing down trees and building dams out of the acquired material, beavers have an enormous impact on the flow patterns of rivers, streams, and creeks. For instance, by holding back the flow of water immediately upstream of the dam, areas of deep, barely flowing water called pools are formed, which are attractive to many kinds of fish as both resting and feeding habitat.  

 

Similar in appearance and habits to the North American Beaver, the Eurasian Beaver (Castor fiber) can be found across most of continental Europe and eastward into China, Mongolia, Siberia, and Russia. Together, the North American and Eurasian beavers represent the two species of beavers which are currently known worldwide.

 

Beavers teach us the magnitude of impact that small creatures can have on the environment around them. In the same way, while the world we live in is too titanic, too daunting, for our own actions to matter, if we work hard and put our efforts in the right direction, we may be able to create more change than we realize.

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References

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https://www.beaversolutions.com/beaver-facts-education/beaver-behavior-and-biology

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https://nationalzoo.si.edu/animals/beaver

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https://www.hww.ca/en/wildlife/mammals/beaver.html

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https://www.wildlifeonline.me.uk/animals/species/eurasian-beaver

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Photo credit

US National Park Services Gallery: North American Beaver (Castor canadesis), Acadia National Park 2015 

https://picryl.com/media/north-american-beaver-castor-canadensis-acadia-national-park-2015-04f87d

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