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Kangaroos: Their Unlikely Biology

Animals with Insane Biology: Kangaroos

By Althea MarchPublished 10 months ago 11 min read
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Kangaroos: The Insane Biology

Australia is known for having a lot of wildlife that tries to kill you. For example, octopuses with blue rings, saltwater crocodiles that prowl the estuaries, bull sharks and box jellyfish that frolic along the coastline, and funnel web spiders contain a deadly neurotoxin. While huntsman spiders are less likely to cause serious illness, they are far more likely to terrify humans with their speed and size.

The incredibly venomous inland taipan and its close relatives that live on other parts of the continent are real, but occasionally the most unexpected species can turn violent if you wander through the grassy fields of Australia. You might come across a scene like this where a kangaroo is waiting chest deep in the water with a look on his face that says, “Come on in, the water's great.” If the kangaroo succeeds in luring its opponent into the water, it will ferociously drown it by holding its head underwater until it's no longer putting up a fight.

Many dogs and dingoes have met their end in this way. Even in 2022, a man was even killed when he suffered extensive head injuries including a broken jaw as he attempted to rescue his two dogs from a large kangaroo. These fluffy grass eating hopping animals who fill the same ecological niche as deer do in other parts of the world, can also be quite dangerous.

It's rare for kangaroos to murder someone, and only around five individuals a year seek medical attention following a kangaroo interaction, but they are definitely capable of doing so because battling for dominance in the kangaroo world is common and is similar to the animal version of MMA kickboxing. The fight typically begins with one male slapping another in the face. Both of them stand up tall, lean their heads back, and begin to grapple with their hands to take down their opponent. The next maneuver is the kick, which may deliver a devastating blow due to their enormous leg muscles and gigantic claws.

The strength, aggressive behavior, and peculiar physiology of kangaroos make them a force to be reckoned with. Kangaroos, wallabies, betongs, kawacas, and rat kangaroos are all members of the macropod family. A kangaroo like this would be enough to disembowel a human. During the hitting and kicking, the kangaroos try to wrestle each other to the ground, where eventually one will give up and there will be a winner.

The larger kangaroos and wallabies are descended from one line, while the smaller, mouse-like marsupials, such as potteroos and betongs, descended from another. In fact, there was even a brief period, some 15 million years ago, when a carnivorous species of kangaroo hunted other creatures.

Marsupials and placental mammals diverged from a common ancestor more than 125 million years ago, and the reproductive strategies of marsupials evolved to be extremely different from ours at that time. Today there are six species of kangaroos across Australia and New Guinea and they all belong to the marsupial family who are known for carrying their young in pouches.

Kangaroos give birth after just a month of pregnancy, and their young are among the largest and most developed of any marsupial. Despite the fact that they're still blind, furless, barely able to move, and weigh less than two pounds or less than one kilogram, once they're born, they crawl into their mother's pouch where they spend another six months feeding off her milk and finishing their growth.

Once they're out of the pouch, they become what's called “young at foot,” and that's when the Joeys really start developing the skills that make them such formidable fighters and incredibly efficient hoppers. Based on the fossil record, it seems that hopping, as a form of locomotion, appeared about 20 million years ago.

But it wasn't until much more recently that the fastest of the modern species, red kangaroos, appeared, and it's this largest of the kangaroos that scientists have been studying for decades because hopping is rare among vertebrates and is primarily used by frogs and small mammals. Nothing else anywhere near the size of a red kangaroo hops, yet these marsupials reach great speeds doing so.

In 1973, a group of researchers taught red kangaroos to hop on a treadmill and wear a mask. While doing so in order to measure their oxygen consumption, most mammals, the faster they run, the higher the energy costs for the body. But the opposite is true for kangaroos. Their energy and oxygen requirements are high when they start hopping. But as they go faster, those aerobic demands don't change. Hopping at speeds of 15 kilometers per hour is much less energy costly for kangaroos than for other mammals of similar sizes.

They can comfortably hop at speeds of 20 to 25 kilometers per hour for quite some time, if they're being chased by predators and really need to sprint. They can attain speeds of 65 to 70 kilometers per hour, which puts them among the fastest land animals in the world. Their speed and energy efficiency are the result of a number of adaptations.

First, there's the size of their hind limbs, which are twice as long as their forelimbs. These give them a base from which to spring off, essentially using a bipedal form of movement. Then there are the tough tendons of their ankles and knees. These elastic bands store energy in a way that doesn't rely exclusively on mechanical muscle movement. but their muscles are impressive too.

The skeletal muscle mass of red kangaroos is about 50 percent of their total body mass, making them among the buffest of mammals. First, large mammals, like humans and cows, only have 35 to 40 percent of their muscle mass made up of skeletal muscle, and for kangaroos, the majority of that muscle is centered around their pelvis and hind limbs, where they need to generate the spring for their hopping. Kangaroos also have a high density of mitochondria in their muscles, as well as a high level of capillary density and blood volumes. Basically, this means their muscles are supercharged like those of a racing horse.

All of these features enable kangaroos to outrun most predators and move over great distances in search of food, but when they move more slowly, they look downright awkward and surprisingly, this slow movement requires a lot more energy. Their walking is known as pentapedal locomotion, referring to five feet since the kangaroo's large tails swing in the opposite direction of their torso.

As we just established, kangaroos are essentially the Australian equivalent of deer herbivores, living in huge groups called mobs and grazing on grasslands. However, there is one key distinction between kangaroos and other grass eaters. For animals that eat grass and leaves, such as kangaroos, it can be challenging for the body to break down so much fiber.

While ruminants like cows, sheep, and deer have four stomach compartments and will regurgitate food in order to chew it a second time (a process known as rumination), kangaroos only have two stomach chambers and do not chew their cud. Instead, food moves along this system almost like a conveyor belt rather than being stirred over and over.

Although kangaroos can spend up to 10 hours a day grazing and rely heavily on their food for moisture, they can go days or even weeks without drinking as long as they are still eating.

Another significant difference between the digestion of kangaroos and ruminants is how the fermentation process works. In order to extract nutrients from all those high-fiber greens, bacteria in these animals’ digestive systems help break down the food for ruminants. In this process, bacteria transform the hydrogen gas into methane, which the animals then fart or burp.

Methane is a greenhouse gas that's 30 times more potent than carbon dioxide, and 50 to 60 percent of it comes from the agricultural sector and the digestion of ruminating animals. Since people like eating meat so much, this is a major problem. Scientists have been experimenting with ways to get the animals burping less dangerous gases, which is what led them to study kangaroos, whose digestive fermentation process doesn't release nearly as much methane, about 27 percent the amount of ruminants.

There are a couple reasons for this. One is that the food moves more rapidly through the digestive tract of kangaroos, which washes out some of the bacteria that might otherwise produce methane. But other research has found that kangaroos have a different kind of bacteria in their guts.

Fermentation always produces hydrogen gas, but instead of bacteria that turn it to methane, kangaroos have bacteria that turn the gas into acetic acid, which helps in muscle growth. This leads us right back to where we started, the Incredible strength of kangaroos, although different species of kangaroo grow to be different sizes, all of them are pretty big.

The male red kangaroos, which are the largest, can grow to be absolutely massive. An adult male can weigh 90 kilograms and stand over 2 meters tall, which makes them significantly larger than the average human.

Starting from the time they're young, all types of kangaroos put their muscles to use by learning how to fight early in life. Joeys will fight while playing, usually with their mothers, learning how to move their limbs around. Play fighting continues throughout the lifespan of a kangaroo. The adult males often engage in ritualized fights, where the goal isn't really to hurt one another, so much as to hone their skills.

Even females will fight by playing, though it's less frequent. When things get more violent, this is when kangaroos are trying to get access to something like water or mating rights with females. Scientists have found that different species have different styles of fighting.

Those who are slightly smaller break contact frequently and are more likely to kick each other. These kicks can be so damaging, that males have evolved hardened, dermal shields on their bellies to avoid being disemboweled. For larger species like red kangaroos, the main form of fighting is grappling with the head, neck, and shoulders. The goal is to throw down the opponent and the kangaroos do so by whatever means necessary.

Kangaroos will also occasionally fight off predators like dingoes, though they're just as likely to hop away to avoid being caught. In some cases, as mentioned before, they'll even head for the closest watering hole and drown any animal that gets too close to them.

In reality, this is a defensive maneuver, as it's only trying to protect itself from attack, and it's a strategy that can backfire. If the water is very shallow or very deep in those cases, the kangaroos don't have as much of an advantage and can easily be bitten or drowned themselves.

Although the kangaroos are backed mainly because of their need to fight and flee, the muscles also seem to give them an advantage with the ladies. Male kangaroos will occasionally stand in a way that accentuates their muscles to attract females and demonstrate that they are strong enough to handle outsiders. But those bulky muscles come at a price: adult males are more likely to perish during droughts and other times of environmental stress, possibly because their bodies need more energy to maintain. Nevertheless, so far, this tactic has worked well for kangaroos, especially males, the gigantic, the perceptive, the frightening, the strange, and the buff.

Respect for the natural world soars. You have surely been amazed at the complexity of evolution and amazed that the laws of physics could allow for such a variety of life on this planet. Although the never-ending conflict between predators and prey is exciting, understanding differential equations allows you to develop mathematical models for various scenarios to determine.

For example, how an increase in dingoes will influence the local kangaroo population. When you understand geometry, you can see that something as seemingly cool as a nautilus shell is actually an amazing example of a logarithmic spiral.

Math helps us see the patterns and realities of the universe, which is brilliant. Other examples of fractals in nature include towering trees, flowing rivers, flowers, and broccoli heads. Interactive lessons covering everything from basic geometry and algebra to advanced differential equations and calculus are available. You can also explore neural networks. They are occasionally difficult, with an in-depth explanation to lead you to the correct answer so you can learn from your mistakes.

Data science or even advanced physics are all of which help us understand the world we live in and help us write this article. It's simple to learn in this relaxed atmosphere, and most importantly, it's simple to learn by doing, which is why the use of interaction in geometry makes perfect sense. Try everything with geometry, which uses tiling puzzles and sliding scales to help you comprehend the geometry of honeycombs and many other lovely patterns you find in the world around you.

Nature
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About the Creator

Althea March

I am a writer who searches for facts to create compelling nonfictional accounts about our everyday lives as human beings, and I am an avid writer involved in creating short fictional stories that help to stir the imagination for anyone.

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