Kangaroo: Characteristics, Habitat, Reproduction, Feeding

The kangaroo is a marsupial that belongs to the Macropodidae family. Among its distinctive features are its long and powerful tail, which is used as an additional limb, and the disparity in the development of its legs. The rear ones are big and strong, while the front ones are smaller.

Another characteristic that identifies it is that females have a bag of skin in the abdominal region, known as a pouch. In this, the newborn calf completes its postnatal development.

Kangaroo. Source: pixabay.com

Commonly, the term kangaroo is used to describe the largest species in the family, such as the eastern gray kangaroo and the red kangaroo. The smaller ones are called wallaby, one of the representatives of this group being the black wallaby.

The means of locomotion of this mammal is jumping, for which it uses the strong muscles that make up its powerful hind limbs. When the animal is moving at a slower speed, it uses pentapedal locomotion. In this, the tail functions as a fifth leg, contributing to movement.

The kangaroo is native to Australia, where it inhabits open areas of forests, in grasslands, scrublands and plains.

Article index

  • one

    Evolution

  • two

    General characteristics

    • 2.1

      – Extremities

    • 2.2

      – Tail

    • 23

      – Body

    • 2.4

      – Fur

    • 2.5

      – Size

    • 2.6

      – Teething

    • 2.7

      – Locomotion

  • 3

    State of conservation

    • 3.1

      Threats

    • 3.2

      Vehicle collisions

  • 4

    Habitat and distribution

    • 4.1

      Western gray kangaroo

    • 4.2

      Agile wallaby

    • 4.3

      Lumholtz Tree Kangaroos

  • 5

    Taxonomy and classification

  • 6

    Reproduction

    • 6.1

      Fertilization

  • 7

    Feeding

    • 7.1

      Digestive process

  • 8

    Behaviour

    • 8.1

      Fights

  • 9

    References

Evolution

The fossil record shows evidence of the existence of giant kangaroos during the Pleistocene and Pliocene. Relative to the smallest ancestors of kangaroos, they lived on the current Australian continent around 20 million years ago.

Kangaroos, like other macropodids, share an ancestor with the marsupial family Phalangeridae. This ancestor, which existed in the mid-Miocene, lived in the treetops. Its teeth were short, suitable for eating the leaves of shrubs and trees.

At the end of the Miocene and until the Pliocene and Pleistocene, the climate underwent great changes, becoming dry. This caused the near extinction of the forests and the growth of grasslands. At the same time a radiation of macropodids occurred, which had adapted to a diet of woody herbs.

This group of marsupials had teeth with high crowns, a must for animals that include rough vegetation in their diet.

Species related to wallabies and modern gray kangaroos began to appear during the Pliocene. The most recent evolution is that of the red kangaroo, whose fossil record dates back 1 to 2 million years.

General characteristics

Male Red Kangaroo (Macropus rufus)

– Extremities

The hind legs are long, narrow and powerful, with four toes each. The fourth toe bears much of the body’s weight, while the second and third are attached and are vestigial, a condition known as syndactyly.

As for the forelimbs, they are short and have five separate fingers, including a non-opposable thumb. Each finger ends in a sharp claw. They have strong muscles, especially in males, since they use these legs to fight and demonstrate their dominance in front of the group.

Kangaroos have large, elastic tendons on their hind legs. In these, the elastic tension energy is stored, which is used in each jump performed. The rebounding movements occur by the spring action of the tendons, rather than being a muscular effort.

– Tail

The kangaroo is characterized by its muscular tail, which has a thick base. In the red kangaroo, this structure is made up of more than 20 vertebrae, covered by strong muscles. This helps the animal maintain its body balance and also intervenes in pentapedal locomotion.

In addition, the tail helps to conserve energy, since its propelling force is much greater than that generated by the front and rear legs, combined. In this way, the kangaroo maintains its energy regardless of the force it has exerted with its tail.

– Body

The shape of the body characterizes and distinguishes the macropodids. The head is small, compared to the body. It has large and flexible ears, which can rotate to better capture sounds emitted at long distances.

Their eyes are large and are located on both sides of the head, which gives them binocular vision. In addition, it has excellent nighttime visibility, which makes it easier for them to locate their food at night.

As for the snout, it is long and has a small mouth at its end. In this you will find a specialized denture, which makes it easier for you to cut and chew woody plants. The lips are thick and the upper one is divided.

Females have an open fold of skin across the front, covering all four of their nipples. In this pouch or bag, the young culminates its development, in addition to serving as a refuge, even when it is larger and consumes solid food.

– Fur

Kangaroo hair is generally short, woolly, and smooth. Its coloration varies according to the species, however, it is usually coppery-brown and grayish tones, alternated with white hairs that give it a grayish appearance. Some may have stripes on the head, hind legs, or back.

Thus, the red kangaroo ( Macropus rufus ) has a reddish-brown fur, while that of the female is gray or bluish. The ventral area and the inner part of the limbs are clear. As for the eastern gray kangaroo ( Macropus giganteus ) they have a light brown or gray coloration.

– Size

The size of the kangaroo varies by species. The largest is the red kangaroo, whose body has a length, from head to rump, of 1 to 1.6 meters. The tail measures 90 to 110 centimeters. As for its weight, it is around 90 kilograms.

One of the smaller species is the rock brush-tailed wallaby ( Petrogale penicillata ), which is between 50 and 60 centimeters long, with a tail of approximately 60 centimeters. Regarding the weight, this varies from 3 to 9 kilograms.

– Teething

The largest species have complex teeth, which have a high crown. The molars have transverse ridges, so the harder grass is cut between opposing teeth. In addition, the growth of the teeth is continuous.

– Locomotion

Jump

Kangaroos use jumping as a means of moving from one place to another. They can do it at different speeds, according to their need.

Thus, the red kangaroo usually moves between 20 and 25 km / h, however, in short distances it could jump at a speed of up to 70 km / h. In addition, this species is capable of maintaining a constant rhythm over long distances, traveling almost 2 kilometers at a speed of 40 km / h.

During this displacement, the strong gastrocnemius muscles lift the body off the ground, while the plantar muscle, which joins near the fourth toe, is used for the lift-off action. The potential energy in this movement is stored in the elastic tendons.

There is a very close link between breathing and jumping, which provides high energy efficiency for this type of locomotion.

At the moment that the legs are raised from the ground, the lungs expel the air, while when the animal places its limbs forward, ready to land, these organs are again filled with air.

Pentapedal locomotion

When the kangaroo travels at slow speeds, it uses pentapedal locomotion. For this, it uses its tail, forming a tripod with its front legs, while bringing the rear legs forward. This move, like the jump jump, are energetically expensive.

In this movement, the tail plays a fundamental role, since its propulsion force is much greater than that exerted by its rear and front legs.

I swim

This mammal is an expert swimmer, being able to flee into the water to avoid being captured by a predator. If it were to chase it, the kangaroo can grab it with its front legs to hold it underwater and drown it.

State of conservation

Kangaroo populations have declined, which means that many species are threatened with extinction. However, most of this group is listed by the IUCN as of Least Concern.

For this categorization, its great spatial distribution and the few threats that affect this species were considered.

Threats

Poaching to obtain and market meat is one of the main problems that afflicts the kangaroo. In addition, their skin is often used to make leather goods.

In New Guinea, Macropus agilis is locally threatened by persecution and excessive capture, especially in populations located in the southeast of the region.

This species, like Macropus rufogriseus , is considered a pest in some areas of Australia, which led to some control measures to avoid larger ecological alterations.

Another factor that affects population decline is the fragmentation of its habitat. In this sense, the construction of roads not only alters the ecosystem, but also constitutes a dangerous element when the animal tries to cross it.

Vehicle collisions

When the kangaroo is close to the road, the noise of the engine or the light of the headlights frightens them, and can cause them to make an abrupt jump in front of the car. In addition to causing the death of the animal, as a result of the rolling over, the strong impact of the jump can cause serious damage to the vehicle and its occupants.

This is why in regions where kangaroos are abundant, there are numerous signs indicating their possible crossing on the road. These signs often include multiple phone numbers where people can call to report the accident and injured animals.

Habitat and distribution

Most kangaroos live in Australia, where they can inhabit a variety of regions, including Tasmania, New Guinea, and some island territories.

Generally, some species live in forests, in the Savannah desert, and others in the plains, where grass is abundant. However, each has its own distribution and habitat preferences.

Western gray kangaroo

Photographs by JarrahTree… commons.wikimedia.org [CC BY 2.5 au (https://creativecommons.org/licenses/by/2.5/au/deed.en)]

The western gray kangaroo ( Macropus fuliginosus ) is endemic to southern Australia, where it occurs from the Indian Ocean to western New South Wales and Victoria and New South Wales.

In relation to the ecosystems it occupies, there are scrublands, grasslands and open areas of forests.

Agile wallaby

Donald Hobern from Copenhagen, Denmark [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)]

The Macropus agilis  has a very wide distribution. This kangaroo is found in southeastern New Guinea, Indonesia, and Papua New Guinea. It also inhabits Goodenough, Fergusson, and the Kiriwina Islands.

It also lives in large territories to the north of Australia, with some isolated populations on the southern and northern Peel, Stradbroke and Groote islands. It can be found in New Ireland and the Normanby Islands, as well as having been successfully introduced to Vanderlin Island.

The agile wallaby prefers lowland savanna grasslands. It is also all along streams and rivers, in open places in forests. However, it can live in coastal sand dunes and inland mountainous regions, where it takes refuge in dense vegetation.

Lumholtz Tree Kangaroos

DiverDave [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]

The Dendrolagus lumholtzi is a tree kangaroo found in the rainforests between Mossman and Ingham, northeast Queensland. Currently their range of occupation has decreased in the Australian highlands, due to habitat destruction.

This species, mainly arboreal, lives in the tropical forest and along the riparian vegetation, in open habitats. Less frequently it is located in the humid sclerophyllous forests that form the Atherton Plateaus.

Taxonomy and classification

  • Animal Kingdom.
  • Subkingdom Bilateria.
  • Chordate Phylum.
  • Vertebrate Subfilum.
  • Tetrapoda superclass.
  • Mammal class.
  • Subclass Theria.
  • Infraclass Metatheria.
  • Order Diprotodontia.
  • Suborder Macropodiformes.
  • Family Macropodidae.

-Subfamily Sthenurinae.

Genus Lagostrophus.

-Subfamily Macropodinae.

Genders:

Dendrolagus.

Wallabia.

Dorcopsis.

Thylogale.

Dorcopsulus.

Setonix.

Lagorchestes.

Petrogale.

Onychogalea.

Macropus.

Reproduction

The female usually becomes sexually mature between 17 and 28 months of age, while the male can reproduce for the first time at approximately 25 months.

During courtship, females in heat roam the territory, attracting males, who watch over them and follow their movements. They sniff your urine to check that they are in heat.

When he gets a female, the male approaches her slowly, to avoid scaring her. If she doesn’t run away, he licks her, scratches and scratches her gently, and then copulates. Because the larger male pairs with females that are in heat, the younger ones do so with those that are close to having it.

Fertilization

In the fertilization process, the ovum descends to the uterus, where it is fertilized by sperm. The development of the embryo occurs rapidly, in the red kangaroo, the calf is born 33 days after fertilization.

Generally, one calf is born at a time. This is blind and hairless. The hind legs are not well developed, while the forelegs are strong, allowing it to climb the skin of the mother’s abdomen and reach the pouch.

Once in the pouch, it attaches to one of the four nipples and begins to feed on breast milk. Almost immediately, the female can become sexually receptive to the male after giving birth.

If this new egg is fertilized, the embryo enters a physiological stage of inactivity, until the moment in which the young in the pouch completes its development. This reproductive condition is known as embryonic diapause.

The hatchling in the bag continues its development and after 190 days it emerges from the bag. However, it doesn’t completely quit until about 7 to 10 months have passed.

Feeding

Kangaroos are herbivorous animals. Within their diet they include herbs, moss, flowers, tree leaves and sporadically they could consume some fungi.

The diet varies in each species and will depend on the environmental characteristics of the habitat where it is found. In this way, the eastern gray kangaroo mainly eats a wide variety of grasses, while the red kangaroo includes large amounts of shrubs in its diet.

Many species have nocturnal and twilight habits, so during hot days they are generally resting. At night and in the morning, where the temperature is lower, they move around the territory in search of their food.

Digestive process

Your body has undergone some highly fibrous, diet-based adaptations. Among the structures that have undergone modifications are the teeth. As the kangaroo matures, the front molars wear out, so they cyclically undergo replacement.

In the process of change, the posterior molars sprout from the gum, thus pushing the rest of the molars forward. In this way, molars that are worn and are no longer functional, fall forward.

The posterior molars erupt through the gums, pushing the other molars forward and forcing the worn front molars to fall out. In this way, the kangaroo always has sharp teeth in advance.

As for the stomach, it has two chambers: the tubiform and the sacciform. The frontal cavity, which is shaped like a sac, contains abundant bacteria inside. These are in charge of starting the fermentation process of food.

The kangaroo may regurgitate part of the food, to contribute to the breakdown of cellulose molecules. After the fermentation process, the already fermented food goes to the second chamber, where the enzymes and acids culminate in the digestive process.

Behaviour

Kangaroos are social animals and form groups, called herds. The members of these take care of and protect each other. If anyone notices the presence of a threat, they hit the ground hard with their powerful hind legs, alerting the rest.

A common behavior within the group consists of sniffing and touching the nose of the new members, thus obtaining information from them. There is a strong bond between mothers and their young, which is reinforced through the grooming they perform on the young.

Fights

Aggressive behaviors have been described among the vast majority of species. These fights can be momentary or they can be part of a long ritual. In highly competitive situations, such as when males fight for a female in heat, the fight is brief.

However, males often engage in a ritualized fight, which could arise suddenly when foraging together or when two males scratch and groom each other. The combatants grab their necks and touch each other on the head and shoulders, using their front legs for this.

In addition, they can act trying to push the opponent. On some occasions, defiant behavior may be rejected, especially if an adult male is threatened by a younger one. Whoever interrupts the fight or abandons it will be the loser.

These fights are used to establish levels of hierarchies between the males. Said dominance is ratified when in most of the times the winners displace the loser from the rest areas.

References

  1. Wikipedia (2019). Kagaroo. Recovered from en.wikipedia.org.
  2. Alina Bradford March (2016). Kangaroo Facts. Lives cience. Recovered from livescience.com.
  3. Kristie Bishopp (2017). The Digestive System of a Kangaroo. Sciencing. Recovered from sciencing.com.
  4. ITIS (2019). Macropodidae. Recovered from it is.gov.
  5. Burbidge, A., Menkhorst, P., Ellis, M. & Copley, P. 2016. Macropus fuliginosus. The IUCN Red List of Threatened Species 2016. Recovered from ucnredlist.org.
  6. Dannie Holze (2014). Kangaroo Tails. California Academy of Science. Recovered from calacademy.org.
  7. (2019). Kangaroo habitat. Recovered from kangarooworlds.com

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