Body Designed for Fast, Efficient Swimming

a gray shortfin mako shark swims in sunny waters near the Western Cape in South Africa

Biological Strategy

Short-finned mako shark

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Image: wildestanimal / Shutterstock / Some rights reserved

Modify Speed

Modifying speed or magnitude of velocity is important for some living systems because it enables them to control their movement to access resources, escape predators, and more. Modifying speed requires not only overcoming inertia, but also minimizing the energy needed to make the change. Therefore, living systems have strategies to safely shift from fast to slow or slow to fast. An example is a bird called the kingfisher, which streamlines its body and feathers to quickly move from hovering over water to diving through the air and into the water. Once in the water, the kingfisher slows down by spreading its wings to avoid diving too deep.

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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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Fish

Class Agnatha (“without jaws”), Class Chondrichthyes (“cartilage fish”), Superclass Osteichthyes (“bone fish”): Sharks, eels, snapper, hagfish

The fish are a diverse group, comprising multiple classes within Phylum Animalia. The most well-known classes are Chondrichthyes, which has sharks and rays, and superclass Osteichthyes, which has all bony fish like cod and tuna. Unlike other vertebrates, fish only live in water. They use special adaptations like fins, gills, and swim bladders to survive. Most are ectothermic, meaning their body temperature depends on the water temperature around them. Over half of all vertebrates are fish. They’re found from the bottom of the sea to high mountain lakes.

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The bodies of shortfin mako sharks and some tuna are designed for fast, efficient swimming thanks to internalized red muscle associated with a force-transmission system.

“Through distinct evolutionary pathways lamnid sharks and tunas have converged on the same mechanical design principle, that of having internalized red muscle associated with a highly derived force-transmission system, two features that form the basis for their thunniform swimming mode. Our study shows that not only have the physical demands of the external environment sculpted the body shapes of large cruisers, but also the internal physiology and morphology of their complex locomotor systems has been finetuned over the course of their evolution.” (Donley et al. 2004:64)

Last Updated August 18, 2016

References

Journal article

Convergent evolution in mechanical design of lamnid sharks and tunas

Nature | 05/05/2004 | Jeanine M. Donley, Chugey A. Sepulveda, Peter Konstantinidis, Sven Gemballa, Robert E. Shadwick

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