# Kangaroos - An Informative Essay



## voorhees14

Australia is the driest, flattest, oldest, and most formidable continent in the world. Its harsh interior is dominated by an arid desert region known simply as the Outback. This rough, barren wasteland is one of the most unwelcoming places on Earth; in fact, it ranked third in the travel guide The 101 Most Dangerous Places in the World, by Robert Young Pelton. This, then, would lead one to believe that the inhospitable Outback is practically uninhabitable—by humans, or any other form of animal. However, surprisingly, this is not the case. The Outback is teeming with animals of all varieties, from reptiles to birds to koalas to kangaroos. These animals, completely isolated from the rest of the world, were allowed to take their own evolutionary path and as a result are like no other animals on the face of the planet. They were, and still are, able to survive in the incredibly harsh, arid conditions of the vast Australian interior because they are highly evolved, acutely specialized species of animals that, over the years, have learned to adapt and adjust to the environment around them. From mammals that lay eggs to birds that cannot fly, this evolutionary process is clearly visible throughout Australia’s wildlife. But perhaps the most highly evolved of all Australian creatures is the kangaroo, who began the gradual evolutionary process over 25 million years ago. The adaptability that is so prevalent among the animals of the Outback is epitomized in the kangaroo, Australia’s national symbol, through its highly specialized anatomy, its unique and peculiar feeding habits, and its distinctive reproduction and breeding patterns. 
	The kangaroo is so highly specialized that nearly every single part of its body and every aspect of its anatomy contributes in some way to its overall survival. To begin with, the kangaroo possesses large, uniquely shaped, flexible ears, which enable it to detect faint or distant sounds, such as the approach of an enemy or fellow kangaroo. This animal also possesses a keen sense of smell, thanks to its finely tuned nose, which is important because kangaroos use urine, feces and other secretions to mark important locations. Next, the kangaroo’s unusual method of traveling, hopping, is enhanced in many ways by its unique anatomy. Even the earliest European explorers of Australia noticed the kangaroo’s unusual anatomy, and its relationship to the animal’s remarkable transportation method. Joseph Banks, the naturalist onboard Captain James Cook’s ship, put it this way:

To compare it to any European animal would be impossible—its
fore legs are extremely short and are of no use to it in walking; 
its hind legs again are disproportionately long; with these it hops 
7 or 8 feet.

At cruising speed, kangaroos go approximately 20 miles per hour, although they are capable of hopping at speeds of over 40 miles per hour, thanks to their incredibly powerful and muscular hind legs. The hind legs of kangaroos contain almost twice the muscle mass of other animals their size. This enables these animals to travel long distances without tiring. Kangaroos are also capable of making leaps of up to 40 feet, the length of a long school bus, and some of the larger species can clear 10-foot fences from a standing position. Another feature that enables a kangaroo to hop so effectively is its large feet. These long and narrow feet give a kangaroo stability when hopping and act as a springboard for the kangaroo to push off. The feet also serve as weapons for male kangaroos. In fact, one kangaroo that escaped from a zoo in Adelaide knocked out a policeman with one kick from its feet before it was recaptured. The last (and perhaps most extraordinary) part of the kangaroo’s anatomy that contributes to its overall success is the tail. The tail of a kangaroo is almost as long as the body and serves many purposes. When a kangaroo is hopping at full speed, the tail stretches out behind and tips upward slightly in order to counterbalance the kangaroo and ensure that it does not fall forward. Additionally, when a kangaroo is walking, grazing, or socializing, the tail acts as a stabilizer or third leg, because although kangaroos’ hind legs are ideal for speed, they are not as effective for walking slowly, and additional support is necessary. Lastly, male kangaroos use their tail in fights. They lean back on their tail, putting all of their weight onto it, and then kick out at the opponent with their powerful hind legs. But while the kangaroo’s anatomy is undoubtedly spectacular, it is only the beginning of the amazing adaptations that this incredible creature has made in order to survive in the rough Australian Outback.
	The eating habits and diet of kangaroos are another main reason why they have been able to flourish in their seemingly barren environment. Because the desert region of Australia is so infertile and a consistent food source is hard to come by, kangaroos have been able to restrict their nutritional needs to the point where they can survive on almost nothing more than grass and plants. Perhaps author Malcolm Penny put it best, stating simply “the success of the kangaroo(s) may be put down to the fact that its principal food – grass – grows everywhere where the trees are not too thick to prevent it.” The kangaroo has evolved over the centuries to the point that it is very well equipped to handle its diet. Kangaroos have very thin and sharp incisors (front teeth) in both their upper and lower jaws, which enable them to crop grass very low and feed on short, coarse grass which other animals, such as livestock, cannot eat. Kangaroos also possess large molars in the back of their mouths, which chop up and grind tough plant parts. When a kangaroo’s molars become worn out, they move toward the front and fall out. Meanwhile, new molars move in from the back to take their place. A kangaroo will get an average of 16 new molars during its lifetime. The fact that the kangaroo’s main source of food can be found almost everywhere on the continent, combined with the kangaroo’s specialized teeth, has allowed the kangaroos to survive, thrive, and live off the land extremely efficiently.
	The last and most unusual trait that the kangaroo possesses which enables it to survive and flourish in its habitat is its extraordinary reproduction and breeding habits. “Adult female kangaroos,” states writer Patricia Miller-Schroeder, “are, quite simply, baby machines.” Indeed, adult female kangaroos will spend the majority of their adult lives either pregnant or nursing a joey. In fact, it is not uncommon for adult female kangaroos to be pregnant with one baby, have an infant joey nursing inside the pouch, and yet another “at foot” (outside the pouch but still dependent on the mother for milk). In times of drought, however, giving birth would be most disadvantageous for both the mother and the joey, and therefore the mother kangaroo has evolved to the point where she is capable of completely bringing to a halt all reproductive functions in her body until conditions improve. As soon as conditions do improve, however, the cycle will immediately start again from scratch, and within a year the adult female kangaroo will have two developing young, one inside and one outside the pouch, as well as a third on the way. This method of giving birth allows kangaroo populations to stay at full strength in good conditions and enables them to bounce back very effectively from poor conditions or droughts.
	Despite the fact that it lives in one of the most treacherous environments in the world, the Australian Outback, the kangaroo has been able to survive and proliferate, due in large part to the various adaptations it has made over the centuries in order to adjust to its changing environment. From its finely tuned and highly specialized anatomy, to its simple and undemanding diet, to its extraordinary ability to restrict reproduction when necessary, the kangaroo is so acutely evolved and attuned to its surroundings and environment that it is, in essence, part of the Outback. However, certain unnatural circumstances beyond the kangaroo’s control have begun to threaten its survival in recent years. As farmers clear out more and more land in the Outback to make way for grazing pastures, kangaroos have found it necessary to compete with sheep, cattle, and other livestock for grass and water. As a result, kangaroos often invade farmers’ private property, eating the grass and drinking the water that was intended for the livestock. Consequently, farmers have begun to view kangaroos as pests and, for lack of a better way to keep the kangaroos out, will frequently shoot the animals. Researchers estimate that approximately 3 to 5 million kangaroos are killed by farmers each year. Another problem that the influx of humans in Australia has created for kangaroos is road-kills: one observer recently counted 282 kangaroos dead on a 115-mile long stretch of highway in Queensland. However, despite these new and as yet unsolved problems facing the kangaroo population, researchers and scientists are confident that kangaroos will be able to overcome these obstacles and live on as they have for millions of years: adapting to their environment when necessary, evolving to suit their changing surroundings, but always surviving.


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## americanwriter

That opening sentence is a sure argument starter. Good job!

So is that whole "evolution in progress" thread you've got running through this piece. But that's for a theology forum. If you're seeing evolution taking place over there, I think I know a few scientists who'd like a map to a good observation point. They still aren't committing to Darwin's entire theory. 


Interesting piece, none the less. Good luck with it. Thinking of submitting to National Geographic or perhaps Smithsonian Magazine? Animal Planet might even like this as content for their website. Hmm.


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