Animal Adaptations: Structural, Physiological, Behavioral

An adaptation is a trait that helps an animal survive and reproduce in its environment. Adaptations build up over many generations through natural selection, not because one animal decides to change during its own life.

Adaptations fall into three broad categories: structural, physiological and behavioral. This page covers all three, with examples, and corrects two common misconceptions: that an animal can adapt on purpose within one lifetime, and that a chameleon changes color mainly to hide.

What is a structural adaptation?

A structural adaptation is a physical feature of an animal’s body that helps it survive, such as a shape, a covering or a body part.

A thick fur coat is a structural adaptation. Arctic animals with dense fur and layered coats are better able to hold in body heat in cold climates than animals without that fur. This page does not cover plant structural adaptations, such as thick bark or waxy leaves, which work on the same principle but are a separate topic.

What is a physiological adaptation?

A physiological adaptation is a change in how an animal’s body works internally, rather than in how it looks.

Notothenioid fish that live in the freezing waters around Antarctica produce antifreeze proteins in their blood. These proteins bind to small ice crystals that enter the fish and keep the crystals from growing large enough to freeze the fish solid (California Academy of Sciences). This is a body-chemistry adaptation, not a visible one, so it is easy to overlook next to fur or feathers.

What is a behavioral adaptation?

A behavioral adaptation is a pattern of action, not a body part, that helps a species survive.

Moving and living in large groups is a behavioral adaptation. It gives individual animals more eyes watching for predators and more protection for the group as a whole. Behavioral adaptations like this are inherited instincts shared across a species, not habits one animal invents and passes on by teaching.

Do animals adapt on purpose during their own lifetime?

No. An individual animal cannot adapt in the way scientists use the word. Adaptation happens across generations in a population, through natural selection, not as a choice one animal makes to survive.

Natural selection works like this: individuals with a trait that helps them survive are more likely to reproduce, so that trait becomes more common in the next generation (National Geographic Education). No animal changes its own genes on purpose, and a trait an animal develops during its life, such as building muscle from exercise, is not passed on to its offspring. When an individual animal does respond to its immediate surroundings, such as growing a thicker coat for one winter, that short-term change is called acclimation, and it is a different process from adaptation across generations.

Does a chameleon change color mainly to hide?

No. A chameleon’s most dramatic color changes are used for temperature regulation and for signaling to other chameleons, not for matching its background.

Chameleons can shift shades within a narrow range and can darken to absorb more heat from the sun. Males also flash bright colors to defend territory and attract mates, and females use dark coloring to signal they are not available to mate (National Geographic). A chameleon’s resting skin tone does provide some camouflage against its habitat, but the fast, striking color changes people notice are not the animal trying to disappear into a chessboard pattern or any other specific background.

Where can you learn more?

See the animals hub for more animal topics, and how scientists classify animals into groups like mammals, birds and fish. For hands-on material, browse the science printables page. This page is an overview and does not cover every adaptation for every species. It uses arctic fur, icefish antifreeze, group living and chameleon color as one example each.

Sources

• National Geographic Education. Adaptation
• National Geographic. Chameleons’ Craziest Color Changes Aren’t for Camouflage
• California Academy of Sciences. Antarctica’s Antifreeze Fish
• Smithsonian National Museum of Natural History. Explore Animal Adaptations