Skin Protected When Burrowing

a brown and white platypus swimming behind glass at zoo

Biological Strategy

Platypus

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Image: pen_ash / Pixabay / Free non-commercial use

Manage Mechanical Wear

A living system is subject to mechanical wear when two parts rub against each other or when the living system comes in contact with abrasive components in its environment, such as sand or coral. Some abrasive components are a constant force, such as finger joints moving, while others occur infrequently, such as a sand storm moving across a desert. Living systems protect from mechanical wear using strategies appropriate to the level and frequency of the source, such as having abrasion-resistant surfaces, replaceable parts, or lubricants. For example, human joints like shoulders and knees move against each other all day, every day. To protect from mechanical wear, a lubricant reduces friction between the cartilage and the joint.

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Modify Position

Many resources that living systems require for survival and reproduction constantly change in quantity, quality, and location. The same is true of the threats that face living systems. As a result, living systems have strategies to maintain access to shifting resources and to avoid changing threats by adjusting their location or orientation. Some living systems modify their position by moving from one location to another. For those that can’t change location, such as trees, they modify position by shifting in place. An example of an organism that does both is the chameleon. This creature can move from place to place to find food or escape predators. But it also can stay in one place and rotate its eyes to provide a 360-degree view so that it can hunt without frightening its prey.

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Mammals

Class Mammalia (“breast”): Bats, cats, whales, horses, humans

Mammals make up less than 1% of all animals on earth, but they include some of the most well-known species. We know first-hand some of the characteristics that make mammals unique, like having hair, being able to sweat, and producing milk through mammary glands. Another critical shared feature is a set of highly-specialized teeth. Unlike sharks or alligators, for example, whose teeth are generally all the same size and shape, mammals have differently shaped teeth in different areas of the jaws to target specific foods or foraging strategies.

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The extensively webbed feet of the platypus are used for burrowing by folding back the webbing to expose the claws for work.

Image: Niall Kennedy / CC BY NC - Creative Commons Attribution + Noncommercial

This doesnt show the feet as they appear during digging, but you can see how the claws are located so that the webbing can be tucked out of the way.

Image: Leach, William Elford; Nodder, Frederick Polydore.; Nodder, R. P.; Shaw, George / Public Domain - No restrictions

Side-view of platypus shows claws for digging on both front and hind feet. Webbing on the front feet can be tucked away to expose claws for digging.

“As well as being an adept swimmer it is also a powerful and industrious burrower, digging extensive tunnels through the river banks sometimes as much as 18 metres long. To do this, it rolls back the webbing of its forefeet into its palms and so frees the claws for work.” (Attenborough 1979:204)

Check out this related strategy to learn more about how the platypus uses its webbed feet for swimming.

Last Updated May 10, 2018

References

Book

Life on Earth: A Natural History

01/10/1981 | David Attenborough

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