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Marsupial

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Marsupial
Marsupialiacollage.png
Scientific Classification
Orders
Dendrolagus goodfellow eating.jpg
Goodfellow Tree Kangaroo eating

Marsupials are any of the species of mammals belonging to the taxonomic cohort Marsupialia. The word marsupial comes from the Latin word, marsupiālis meaning pertaining to a pouch.[2] The weird thing about this is that they don't have a placenta. Instead of feeding inside the placenta during gestation, they are born earlier and crawl into their mother's marsupium(pouch) or cling to their mother's fur.[3]

The young or 'joeys' are altricial when they're born meaning that they're helpless and are in need of parental care. They are fed there until they are sometimes up to 6 months old, not being fully independent until they are about a year old. Their diets are all different ranging from carnivorous, omnivorous, insectivorous, and herbivorous. They all usually have more incisor teeth than other mammals. Mothers most of the time raise their young by themselves because during the breeding season; males and females breed with each other and then go their separate ways.[4]

Body Design

Female marsupials such as the kangaroo have a pouch on their stomach region to hold their babies or 'joeys' when they are born. They have premature birth and crawl into their mother's pouch to continue growing until they are old enough to be alone. The marsupium (pouch), is a flap of their skin covering their nipples where the joeys get there food from. The milk from the mother give them nutrients to help them grow. Some marsupials do not have a marsupium, but they have exposed nipples to feed their young.[5]

There are features to the koala that help you tell the difference between the male and female. Females have a pouch in the center of their abdomen, males do not. Males have external genitalia that are visible, females do not. Another big difference is adult males have a dark brown scent gland on the center of their white chest, females and young males have a plain white chest. Koalas have a lean, long body and a great sense of balance that helps them to climb trees. Their palms have rough pads that protect them and help them with grabbing hold of trees. Each of their paws has five digits and two of them are opposable and can move opposite to the other three digits.[6]

Wombats are a muscular, stocky marsupial. They have a thick and heavy, barrel-shaped body with a rodent-like face. They have a short neck with a flat head. They don't have great eyesight, but they have very good sense of hearing, smelling, and they can feel vibrations. They have four short and strong legs with muscular shoulders to help them dig. It has thick skin to prevent it from getting injured. Like the koala, it has a rear-facing pouch to hold its young. This is handy for the wombat because when the mother is digging, the dirt doesn't buildup in the pouch. The brain of a wombat is the largest of all marsupials unlike the koala whose brain is rather small for its size.[7]

A wombat has short legs that are strong to help dig.

Life Cycle

Marsupials are mammals that reproduce sexually and that do not have a placenta. Instead of staying inside of their mother's placenta to develop, it crawls into mother's pouch. The marsupial young are basically embryos when they go into the marsupium. The mother has her nipples inside the pouch and so when the young go into it they feed on them to get milk for nutrients from their mother. Some marsupials do not have a true pouch though, it is more like a flap of skin to hold the young, a rudimentary pouch. But, other marsupials do not even have a pouch, instead they are born and then latch onto the mother's nipples until they are developed enough.

The breeding season of most opossums is from as early as December and then goes till around October. The average female opossum can have around 1-3 liters a year. During the mating season, the male opossum makes clicking noises from his mouth to attract the female. The male's sperm is paired in its reproductive tract but when it goes to the female's tract, it can separate. If the eggs become fertilized, they will move from the oviducts to the uteri to gestate for a very short period. After that time, they are delivered from the birth canal.

When the animals are born, they must make the journey of going from the birth canal to the mother's marsupium to continue their development. The mother may help by licking her hair leading to her pouch to make a slicker path for the young to follow. The young stay in the pouch for about 2 1/2 months around when their eyes will start to open. When they leave the pouch, they climb to their mother's back to help learn survival skills and other skills from the mother herself. The young opossum are weaned at around 4 1/2 months and then can start their own mating season to reproduce and repeat the cycle.[8] Depending on the species, marsupials can live 1-26 years. The normal gestation period of marsupials depends on the species, but it can be from 8 to 46 days. The animal's weight at birth is about one percent of the mother's weight for the total litter.[4]

Mother wallaby carrying its joey in its marsupium

Ecology

Today, marsupials are found mainly in Australia and some in the Americas. There are 334 species of marsupials with more than 200 living in Australia but only one, the Virginia Opossum, living in North America.[9] Also some of the other species of opossums can be found in South America. Most marsupials that live in Australia, live in dry climates and desert habitats. The species that live in South America live more in tropical rain forests. There really isn't an exact place that most marsupials have to live, they can live in any part of the forest habitat, from the trees to the floor. The wombat digs with its strong shoulders and burrows underneath the ground. The mountain pygmy-possum is the only marsupial that can live in cold temperatures that get snow and it lives in the Australian Alps.[4]

Many marsupials have a herbivorous diet, but some like the dasyurids are carnivorous.[10] Most of the species that are herbivores eat grasses, leaves, flower nectar, etc. The ones that are carnivorous can rabbits, chickens, other small animals. Some marsupials are even omnivores(eating plants and meat) like the Virginia opossum that eats fruit, eggs, insects, and other small creatures.[3]

Present Day Map of Distribution of Marsupials across the continents

Endangered

Many marsupials are endangered and struggle with being able to survive. Some of the species are hunted for their skins. Other's homes are being taken over by dams and roads being built in the way. Many of these animals have become extinct because they are being hunted down or their homes being taken over by people or even by having competition for their food with new species that are introduced to that area.

Koalas were added to the endangered species list in September 1998 because the area they were living was being populated with more and more people. They were pushed into smaller areas than they're used to and ended up spreading diseases to each other. The eastern quoll, Dasyurus viverrinus, is an extinct animal now to Southern Australia, but is still currently known to live in Tasmania. They too became smaller in size because of factors like population, building of highways, diseases. Another species currently endangered is the bilby. The lesser bilby, Macrotis leucura, is thought to be extinct. The greater bilby is now usually referred to as just the bilby because of the extinction of the lesser bilby in the 1950s. The bilby is harmed by the changes to its habitat and the competition it has with introduced animals to its environment.[11]

Video

Koala Facts

Gallery

References

  1. 1.0 1.1 . Marsupialia Wikispecies. Web. Last Modified 12 May 2014.Unknown Author
  2. Marsupial Dictionary.com. Web. Date of Access 25 January 2015. Unknown Author.
  3. 3.0 3.1 Kindersley, Dorling. MAMMALS Fact Monster. Web. Last Updated October 2013.
  4. 4.0 4.1 4.2 Marsupial San Diego Zoo. Web. Date of Access 11 January 2015. Unknown Author.
  5. Marsupial Encyclopædia Britannica. Web. Last Updated 16 April 2014. The Editors of Encyclopædia Britannica.
  6. Physical Characteristics of the Koala Australian Koala Foundation. Web. Date of Access 11 January 2015. Unknown Author.
  7. Marinacci, Peter.Wombat Physical Characteristics Wombania. Web. Date of Access 11 January 2015.
  8. Reproduction – Life Cycle Opossum Society of the United States. Web. Date of Access 11 January 2015. Unknown Author.
  9. Kelsey, Sam and Mitchell, Stephen. Origin, Diversity, and Ecology of Marsupials University of Bristol. Web. Date of Access 11 January 2015.
  10. Are Marsupials Herbivores Answers. Web. Date of access 25 January 2015. Unknown Author.
  11. Lufcy, Jill.Some Endangered Australian Marsupials semo.edu. Web. Date of Access 26 January 2015. Unknown Author.