Marsupials Essay, Research Paper
Marsupials are pouched mammals. Their young are born in an immature state after a relatively short developmental period in the mother’s uterus. (This is called the gestation period.)
The newborn marsupial crawls into a pouch or onto a pouch-like area on the mother’s abdomen. Here it attaches itself to one of her nipples and remains until it is well formed and has grown much larger.
There are some 250 kinds of living marsupials. These include the Australian and New Guinean insectivorous and carnivorous (insect and meat-eating) marsupials, the omnivorous (plant and meat-eating) bandicoots, and the herbivorous (plant eating) possums, koalas, wombats and kangaroos as well as the South American opossums.
Scientists have grouped them according to differences in their dentition. They are either polyprotodonts (with many teeth and always three pairs of incisors on the lower jaw) or diprotodonts (fewer teeth with only one pair of especially well-developed incisors on the lower jaw).
Characteristics of their pouch, fore and hind foot structure, nature of tail and whether they are tree-dwellers, burrowers or ground-dwellers, help to classify them further
Mammals that can live on land and prey on other animals tend to look similar. The adaptations for chasing, catching and eating other animals are a compact body, four slender limbs, claws and a head with well-developed organs of sight, hearing and smell.
In other words, all the marsupial carnivores are superficially similar and resemble placental cats, shrews, dogs and other animals that share the carnivorous habit.
]There are about 16 living types of kangaroos or macropodoids. “Macropod” means long foot and all kinds have disproportionately large hindlimbs and reduced forelimbs. They are divided into two families. The most familiar family consists of those animals loosely described as kangaroos, wallaroos and wallabies.
The other family includes the much smaller rat-kangaroos, bettongs and potoroos. Sometimes kangaroos are also named according to their habitat, for example, tree-kangaroos or rock-wallabies.
In most kangaroos, the forelimbs are short and are used for manipulating food and scratching. Tree-kangaroos have forelimbs that are slightly longer as an adaptation for climbing.
All kangaroos have a highly developed fourth digit on their hindfoot which has a long pad and a strong claw. Hindlimbs also have syndactylous toes that are used for grooming in much the same way as possums and koalas use theirs.