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  Adaptations
An adaptation is a variation of structure, physiology or behavior that aids the organism’s survival in its particular environment. Below are examples of some of the many adaptations.

Teeth:
  • snakes – teeth slope backward to aid the retention of the prey during swallowing
  • sharks – have two rows of teeth that point backward to hold prey; also, teeth are replaced frequently throughout an animal’s lifespan
  • toothed whales (such as dolphins, porpoises, and sperm whales) – usually only have teeth on the bottom to catch prey, which they swallow whole
  • baleen whales (such as right whales and blue whales) – have hundreds of thin plates called baleen, which they use to filter plankton from the water
  • carnivores (such as dogs and lions) – pointed “canine” teeth specialize in ripping and tearing food and large molars crush bones
  • herbivores (such as deer and horses) – incisors clip off grass and large, flat molars grind food
  • rodents (such as beavers and mice) – incisors are specialized to chisel, usually do not have canine teeth
  • elephants – the tusks are incisor teeth that have grown to be used for attack and defense and for rooting food from the ground and for breaking branches
  • humans – omnivores have several kinds of teeth to perform many functions; tearing, chiseling and grinding
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Digestion:
A group of animals called ruminants are the only vertebrates able to extract the nutrients from cellulose. Cellulose is the component of plant walls and can only be digested with the enzyme cellulase, which vertebrates do not produce. Ruminants have a four-chambered stomach. The first chamber (called a rumen) contains a rich broth of bacteria and protozoa that can digest cellulose. After spending time there, the plant matter (now called cud) is sent back up to the mouth, where the animal chews it again. Then swallowed into the stomach proper where it is digested fully. Ruminants include cows, bison, horses, deer, sheep—all hoofed animals except the pig and the hippopotamus.

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Vision:

  • eyes at the top of their heads – animals that live in the water such as alligators and frogs; also fish that live on the bottom of the ocean floor
  • very large eyes – provide better night vision and better powers of all vision
  • eyes set on both sides of their heads – provide a panoramic view to watch for predators
  • stereoscopic vision – predators and tree-dwelling animals; allows for greater accuracy in determining distances
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Other Senses:
  • octopi can sense polarized light
  • bats use ultrasound to navigate and locate food
  • snakes use heat sensors to detect three-dimensional images
  • birds use magnetism to migrate
  • sharks use a fluid-filled canal along the sides of their bodies to detect movement from vibrations transmitted in water

Water Regulation:
Organisms that live in dry climates must have adaptations that allow them to obtain water. Most animals can get all the water they need by drinking it; however, animals in dry climates can get water from eating fatty seeds, which produce water as a by product of digestion. Other animals obtain fluids from the sap of plants or from the bodies of the animals they eat.

Because of the limited water available, animals in dry climates also have means of conserving water. They are nearly all nocturnal, only searching for food at night when the heat is low. They usually do not have sweat glands. Their urine is highly concentrated and their feces are dry. To prevent water loss through respiration, they have a long nose that cools the air and condenses the water inside the nostril before expelling it to the atmosphere.

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Temperature Regulation – Cold Climates
Animals that live in water usually take on the temperature of the water, which is usually stable. Some large fish and mammals also warm their bodies with muscle activity, fat deposits (called blubber) and thick, waterproof fur. Terrestrial reptiles keep their body temperature stable by absorbing solar radiation during the day. At night they seek shelter to keep warm and to protect themselves during the inactivity that results when they are cooled. Animals that obtain heat from external sources are called ectotherms. Mammals and birds are called endotherms, because they maintain a constant body temperature through metabolism and regulation. Birds use their feathers to protect their bodies. They also migrate to warmer climates. Mammals reduce heat loss in many ways. Below are a few examples.

  • body size – since heat is lost through the surface, the smaller the surface area compared to the volume of the body, the less heat is lost; therefore, animals that live in cold climates are usually much larger than members of the species living in warmer climates
  • body shape – the sphere is the best shape for a small ratio of surface to body volume, and it is therefore the most heat-retentive shape
  • extremities – lose heat first; animals in cold climates have small ears and tails and short legs
  • body coverings – covered with dense, fine fur that holds insulated air close to the body, sometimes this fur even covers the soles of their feet
  • reduction of activity – another way to reduce heat loss is to limit body functions; some mammals hibernate or go into a state of dormancy during the winter months
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Temperature Regulation – Warm Climates
Many of the ways animals keep themselves warm are used in reverse to help them keep themselves cool.
  • shelter – warm climate animals spend the daylight hours hiding in burrows or behind boulders, coming out at night to hunt and forage for food
  • extremities – warm climate animals have long legs and tails, but what is most striking is their very large ears, which are used to cool their bodies by running blood vessels near the surface; the air blowing across the ears cools the blood that in turn cools the body
  • evaporation – means to promote evaporative cooling are also used, including sweating, panting and licking; these methods however, are not good if water is scarce, because they also promote water loss
  • body coverings – most have fine, thin hair as body coverings
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Adaptations to Capture Prey
  • claws
  • tool use
  • mouth parts adapted to grab, hold, bite, pierce, suck
  • toxins to kill or paralyze
  • heat sensors
  • vibration detectors
  • size and strength
  • concealing coloration
  • acute senses
  • behavioral strategies: stealth, cunning, confusion, surprise
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Adaptations for Avoiding Capture
  • speed
  • hiding
  • freezing in position
  • withdrawal into shell or burrow
  • dismemberment
  • counterattack: hooves, horns, wriggling, biting, stinging, concealing color, acute senses
  • behavioral strategies: large herds, warning signals
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