Mammals can be generally classified into three broad groups: egg-laying monotremes, marsupials, and placentals. A marsupial is a mammal that raises its newborn offspring inside an external pouch at the front or underside of their bodies. In contrast, a placental is a mammal that completes embryo development inside the mother, nourished by an organ called the placenta. Both marsupial and placental mammal groups give birth to live young. Each animal in an ecosystem occupies a specific position. Niche is the word used to describe the specific role that an organism (or a population) fills in a specific environment, including the resources it uses and its competitors for those resources.
Placental mammals account for the majority of modern mammal species alive today. Most extant marsupials can be found in Australia and South America although the fossil record shows that they were once more widespread.
SF Table 1.1. Marsupial mammals
Marsupial Mammal |
Niche |
Photo of Mammal |
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Kangaroo |
Large herbivore that forages extensively across open grasslands |
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Wombat |
Medium-sized diurnal herbivore that feeds on grasses, constructs and dwells in extensive tunnel systems |
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Thylacine |
Large, nocturnal fast moving predator that feeds on other mammals |
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Tasmanian Devil |
Stocky nocturnal omnivore that primarily scavenges carrion and feeds on insects and plants |
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Bandicoot |
Small foraging omnivore that eats insects and plants, small rodents, and lizards |
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Quoll |
Small nocturnal carnivore that is an aggressive predator on small mammals, insects, and reptiles |
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Numbat |
Diurnal insectivore that uses a specialized tongue to feed on ants and termites found in decaying wood |
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Dunnart |
Small, nocturnal burrowing insectivore that builds nests of grass and plant material in dry areas |
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SF Table 1.2. Placental mammals
Placental Mammal |
Niche |
Photo of Mammal |
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Antelope |
Large herbivore that forages extensively across open grasslands |
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Groundhog |
Medium-sized diurnal herbivore that feeds on grasses, constructs and dwells in extensive tunnel systems |
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Wolf |
Large, nocturnal fast moving predator that feeds on other mammals |
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Raccoon |
Stocky nocturnal omnivore that primarily scavenges carrion, and feeds on insects and plants |
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Hedgehog |
Small foraging omnivore that eats insects, plants, small rodents, and lizards |
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Weasel |
Small nocturnal carnivore that is an aggressive predator on small mammals, insects, and reptiles |
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Anteater |
Diurnal insectivore that uses a specialized tongue to feed on ants and termites found in decaying wood |
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Mouse |
Small, nocturnal burrowing insectivore that builds nests of grass and plant material in dry areas |
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