Red Kangaroo - The Largest Living Marsupial

Macropus rufus – The Boxing Mammal is Capable of Embryonic Diapause

Oct 9, 2009

Discover how the red kangaroo, the largest of the kangaroo species, lives, fights, jumps, breeds and how it is capable of arresting development of its young in the womb.

Red kangaroos are the largest of the kangaroo species, and they are the largest of the marsupials. Male red kangaroos are orangey-red in color and females are a blue-gray color. Their forearms and underbelly are usually a paler color. They stand from 0.8m (32in) up to 1.8m (6ft) tall and weigh in at 20-90kg (44-180lb). They have strong tails that measure 75-120cm in length.

Kangaroos live in dry conditions in arid and semi-arid zones of Australia. They are able to survive for long periods without water and live on low quality vegetation such as native grasses and shrubs found in the grassland areas they inhabit.

Red kangaroos are not territorial and travel in large groups called mobs. Mobs can contain up to 100 individuals if resources are plentiful. When kangaroos wish to warn others of a potential threat, they stamp their foot or tail on the ground and stretch to full height. Kangaroos are normally gentle animals, however, males will fight each other during mating season to win control of the mob and the females.

Kangaroos fight in a boxing style, punching out with their forearms and kicking with their hind legs while balancing on their tails. When sparring or play fighting, usually kangaroos will only box with the forelegs. In serious fights they will kick with their powerful hind legs. Their huge claws have caused great injury to the curious canine in addition to other kangaroos.

Red Kangaroo Reproduction

Red kangaroos become sexually mature at 2 years of age and can breed throughout the year; however, males don’t produce sperm during prolonged periods of drought. In red kangaroos after the first joey is born and crawls to the pouch, the mother can become pregnant again. Because there is a joey suckling at her already, the new embryo’s development is arrested in the uterus.

This is called embryonic diapause and lasts around 235 days. When the joey leaves the pouch, development of the embryo continues and that joey is born around one month later. Once the second joey is born the mother can become pregnant again and the new embryo’s development will become arrested until the second joey leaves the pouch. The mother can have three joeys at different stages of development to care for, although usually one or two joeys are born each breeding season. Lifespan for the red kangaroo is 27 years.

Red Kangaroo Locomotion

Kangaroos are bipeds and move by hopping or jumping. Muscles in the hind legs of the kangaroo need to generate a lot of power. As a kangaroo lands, tendons in the hind legs store energy that is available for the next jump.

The higher the jump, the more energy the tendons store for the next jump. This makes hopping an energy efficient form of locomotion for the kangaroo because it reduces the total amount of energy needed. Maintaining balance is important for the kangaroo. Its large tail helps with balance when it is hopping and also acts like a tripod leg when the kangaroo is stationary.

When kangaroos graze, they hop around slowly using their small forelegs to support their body while they swing their hind legs forward. Their hind legs are very muscular and allow kangaroos to bound very quickly, up to 48-50km per hour. Single leaps can reach 9m (30ft) in length. Red kangaroos often travel in search of better resources and have been known to cover 200km (125 miles).

Hickman, Roberts, Larson & I’Anson, 2004, ‘Diversity of Animal Life’ in Integrated Principles of Zoology, 12th edition, ed. McGraw Hill, New York, chapter 28.

Campbell and Reece, 2002, 'Sensory and Motor Mechanisms', in Biology 6th edition, ed. Benjamin Cummings, San Francisco, chap 49

The copyright of the article Red Kangaroo - The Largest Living Marsupial in Bipeds is owned by Roberta Goli. Permission to republish Red Kangaroo - The Largest Living Marsupial in print or online must be granted by the author in writing.