Skin Stays Clean

Biological Strategy

Earthworm

AskNature Team

Image: Dan Brekke / Flickr / Some rights reserved

Protect From Dirt/solids

When dirt and other small solids adhere to living systems, they can slow them down, create blockages, reduce their ability to carry out vital functions, or cause surface wear and tear. Due to electrostatic forces, it’s easy for dirt and other solids to adhere to surfaces, so living systems must overcome those forces. An earthworm, for example, uses a small electric current to keep soil particles from adhering to its body as it moves through the soil. This enables it to move more efficiently by reducing drag.

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Animals

Kingdom Animalia (“having breath or soul”): Mammals, reptiles, sponges, corals, insects, birds

This kingdom captures a staggering variety of life—from the smallest coral polyp to the largest elephant. Although animal body shapes and life histories vary, there are a few defining characteristics. Animals are heterotrophs, meaning they gain energy from eating other organisms, and have developed from single-celled ancestors to highly diversified and coordinated multicellular forms. Unlike plant and fungi cells that have rigid cell walls, animal cells are bound by more flexible combinations of proteins. Most animals have cells organized into tissues and are able to move within their environment.

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Skin of earthworms stays clean while moving through moist soil because of electroosmotic flow near the body.

“[S]oil does not seem to adhere to earthworm surface…An important phenomenon of earthworms moving in moist soil is that the electric potential exists on an earthworm tissue…The electroosmotic flow near an earthworm body surface is a basic electrokinetic phenomenon that takes place when the earthworm moves in moist soil. The flow in a micro thin layer of water is formed in the vicinity of the earthworm body surface as a result of the electric double layer (EDL) interaction. Such a micro scale electroosmotic flow plays the role of lubrication between the earthworm body surface and the surrounding medium of moist soil and reduces surface adhesion.” (Zu and Yan 2006:179)

AskNature

Skin Stays Clean

Earthworm

Protect From Dirt/solids

Animals

Last Updated August 18, 2016

References

Numerical simulation of electroosmotic flow near earthworm surface

Scales Minimize Abrasive Damage

Beavers Beat Fires’ After Effects

Body Resists Soil Adhesion

Beaver Dams Cleanse Streams by Slowing Water

Cicada Wings Repel Water, Dirt, Bacteria, and Light

Oyster Reef Shapes Create Safe Havens for Their Young

Term Definition

Skin Stays Clean

Earthworm

Protect From Dirt/solids

Animals

Last Updated August 18, 2016

References

Numerical simulation of electroosmotic flow near earthworm surface

Other Biological Strategies

Scales Minimize Abrasive Damage

Beavers Beat Fires’ After Effects

Body Resists Soil Adhesion

Beaver Dams Cleanse Streams by Slowing Water

Cicada Wings Repel Water, Dirt, Bacteria, and Light

Oyster Reef Shapes Create Safe Havens for Their Young

Term Definition

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