Giraffe Adaptation
Physically and behaviorally well-suited to their environment, giraffes are an extraordinary example of adaptation in the animal world. Inhabiting grasslands and open woodlands throughout sub-Saharan Africa and towering up to 19 feet, giraffes are the world's tallest mammals, weighing an average of 2,800 lbs. Their specialized anatomies facilitate feeding, social hierarchy and defense. With hearts beating at double normal pressure and lungs vastly larger than those of humans but breathing at a much slower rate, giraffes are a marvel of survival and design.
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Neck
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Giraffes' eight-foot necks allow them to reach feeding places that other herbivores can't, according to California's Oakland and Santa Barbara Zoos. WhoZoo, a Texas Wesleyan University website, discounts this theory, citing that giraffes spend half their time grazing below shoulder level. WhoZoo says that giraffes' long necks are a result of sexual selection because bulls use them extensively in "necking," or battling over females. This might explain why males' necks continue to grow after maturity while females' necks do not.
Legs
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Towering over predators and striking out with their forefeet delivering savage blows, giraffes are well-equipped to combat danger. Their forelegs are only one-tenth longer than their hind legs, making them a formidable defense. Despite the much lengthier appearance of the forelegs, this is all the additional protection they need. When their 35 mph speed is insufficient to outrun attackers, giraffes' legs afford them added defense in the form of extremely tough skin and inner fibrous connective tissue that prevents wounds from excessively bleeding.
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Mouth and Tongue
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With specialized mouths, tongues and upper palates, giraffes are undeterred by thorns, devouring up to 140 lbs. of fresh vegetation daily, according to the Oakland Zoo. The animals easily process thorny foods because of their leathery mouths, thick gluey saliva and 18-inch prehensile muscular tongues, the strongest in mammals. Giraffes are ruminants (animals that re-chew partially processed food sent back up from the stomach) and their stomachs have four chambers. They graze 16 to 20 hours per day. They're well-adapted to drought and can go a month without water, relying on the water content of their food and morning dew.
Heart
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Remarkably adapted to their physiology and lifestyle, the giraffe's heart and circulatory system are the most powerful in the animal kingdom. The 2-foot, 24-pound heart requires at least double the normal pressure to pump blood the long way up into the brain. The blood-carrying carotid artery balloons, absorbing increased pressure when giraffes lower their heads. With heads raised, check valves in the jugular prevent sudden dangerous backflow from the head, avoiding unconsciousness and even death.
Lungs
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Although giraffes' lungs are eight times the size of those in humans, their respiratory rate is only one-third the rate of human respiration. This lower rate allows them to avoid windburn to their 12-foot tracheas while inhaling their required massive volume of air. As giraffes breathe, previous oxygen-depleted breaths can't be totally expelled. Consequently, there must be enough lung volume to make "bad air" a small percentage. "The Science Creative Quarterly" explains that without extra air-pumping capacity of oversize lungs, giraffes would breathe the same used air over and over again.
Additional Adaptations
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Giraffes' coloration blends well with their habitat, affording them some camouflage from predators. Their extreme long-range visual acuity helps them keep track of predators and enables communication with other giraffes over several miles.
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References
Resources
- Photo Credit giraffe # 2 image by Kevin Chesson from Fotolia.com
