All organisms have evolved to adapt to their particular environment or ecosystem -- their community of interdependent organisms. When changes in an ecosystem occur, resident organisms must either adapt to those changes or move. Sometimes the changes are big, such as a violent storm or fire that transforms a landscape. Sometimes they are relatively small, like a narrow hiking path cut through a woods. In either case, if the changes affect creatures living in that environment, they adjust either suddenly or gradually through modifications in their species population. Those adaptations can generally be classified as structural, functional or behavioral.
While modifications in behavior can occur within one generation -- for example, a particularly shy species might move deeper into a forest at the encroachment of development -- structural changes can happen more gradually, sometimes over generations. This process of more gradual change is called evolution. To sum it up, genetic variations exist within a population of a species in an ecosystem, and those variations that favor the species’ survival are the traits most likely to dominate a population. As individuals with more advantageous traits -- such as thicker fur in an animal whose ecosystem has become colder -- survive long enough to reproduce, their genetic traits get passed on to future generations. Those individuals with lighter fur might not survive to reproductive age, and their genes do not get passed on. Thus, an increasing number of individuals in that species have thicker fur, altering the traits of that population. If habitat change happens too rapidly, however, a population might not have time to adapt, and extinction may result.
Structural adaptations include physical traits, such as body shape and size, size and shape of body parts, or composition of body parts. For some organisms, their body structures make obvious what kind of habitat they live in or what kind of niche they occupy. A lion, with its sharp teeth and claws, powerful muscles, strong jaw and forward-facing eyes, looks perfectly designed to capture and tear apart prey. A penguin, with its webbed feet, waterproof feathers, streamlined body, oar-shaped wings and layer of blubber, seems well suited to living in frigid water and capturing fish. A penguin's coloring -- light on the belly and dark on its back, making it less visible when swimming to predators from above or below -- might be placed in yet a fourth category of adaptation types, color or camouflage, although structural color, such as iridescence, does occur in some birds, butterflies and other organisms.
Functional adaptations might be less obvious to the naked eye, but they contribute significantly to survival. Marine mammals can go for long periods of time without breathing because they have larger quantities of oxygen-rich blood moving through their bodies, allowing them lengthy diving sessions. During hibernation, a bear can survive 100 days or more without drinking, eating, urinating or defecating. When the external temperature gets too hot for an elephant, its body can direct blood through its enormous ears; the large surface area helps to cool the animal's blood and the body. Photosynthesis in plants, digestive enzymes that help animals break down various foods and the rapid growth cycles of plants in areas with short growing seasons are all examples of functional adaptations.
Migration, hibernation, mating and parenting practices, nest-building and tool use are all behavioral adaptations. The complex social structure in naked mole rat communities -- strangely similar to some insect societies, a phenomenon called convergent evolution -- seems to benefit their populations greatly. An octopus that lives near Australia exhibits a kind of “just-in-case” survivalist mentality, holding coconut shells under its body to conceal itself from possible future encounters with predators. Some adaptations can seem like overkill. When peacocks strut their impressive and ridiculously extravagant tail feathers, they are displaying both behavioral and structural adaptations that help the healthiest males snag mating opportunities with the most peahens. And when pronghorn antelopes in North America gallop at 50 miles per hour -- far faster than any local predators -- it may be a leftover adaptation from a time when American cheetahs, now extinct, pursued their ancestors.
- WWF: Habitat and Adaptation
- Zoological Society of Milwaukee: Animal Adaptations
- Sciences 360: Why some Animals have Forward Facing Eyes and Others Have Sideways Facing Eyes
- New England Aquarium: Penguin Adaptations
- Exploring Nature Educational Resource: Adaptations
- Curiosity Discovery: 10 Ways Life Has Adapted to Its Environment
- The New York Times: The Strange Dark World of the Naked Mole Rat; Jane E. Brody
- National Geographic: Lions, Elephants to Roam the U.S. Plains?
- Churchlands Senior High School: Adaptations
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