Hair Extension and Folding Prevents Speed Loss

Biological Strategy

Whirligig beetles

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Distribute Energy

Many forms of energy are naturally available, including kinetic, potential, thermal, elastic, radiant, chemical, and more. All living systems require energy to carry out their many activities. Energy isn’t a physical object that can be held, so it also can’t be pushed, pulled, or carried. However, it can be transmitted or transformed. For example, the golden-scale snail has a tri-layered shell that dissipates, or transfers, forces from a predator biting down on it, thereby minimizing damage to its soft body inside the shell.

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Move in/on Liquids

Water is not only the most abundant liquid on earth, but it’s vital to life–so it’s no surprise that the majority of life has evolved to thrive on and under its surface. Moving efficiently in and on this dense and dynamic substance presents unique challenges and opportunities for living systems. As a result, they have evolved countless solutions to optimize drag, utilize surface tension, fine tune buoyancy, and take advantage of various types of currents and fluid dynamics. For example, sharks can slide through water by reducing drag due to their streamlined shape and specially shaped features on their skin.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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Hairs on the whirligig beetle's mid and hind legs prevent loss of speed by extending and folding during swimming strokes.

The mid legs and hind legs of the whirligig beetle contain numerous microscopic hairs (called laminae) that increase surface area while swimming, resulting in greater thrust and power. These laminae are dynamic, extending and folding throughout the beetle’s swimming motion to maximize efficiency.

During the power stroke when the beetle swings its legs back against the water, the laminae extend, allowing for a greater push. During the recovery stroke when the beetle pulls its legs back against the water to its starting position, the laminae fold, thereby reducing drag. This enables the beetle to maximize speed during the power stroke while minimizing loss of speed during the recovery stroke.

This strategy was contributed by Rachel Major

Last Updated September 14, 2016

References

Journal article

Experimental Studies and Dynamics Modeling Analysis of the Swimming and Diving of Whirligig Beetles (Coleoptera: Gyrinidae)

PLoS Comput Biol | 29/11/2012 | Zhonghua Xu, Scott C. Lenaghan, Benjamin E. Reese, Xinghua Jia, Mingjun Zhang |

Philip R. LeDuc

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