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Marsupials give birth at a very early stage of development; after birth, newborn marsupials crawl up the bodies of their mothers and attach themselves to a teat, which is located on the underside of the mother, either inside a pouch called the marsupium, or open to the environment. Mothers often lick their fur to leave a trail of scent for the ...
A marsupial has a short gestation period, typically shorter than its estrous cycle, and gives birth to an underdeveloped newborn that then undergoes further development; in many species, this takes place within a pouch-like sac, the marsupium, located in the front of the mother's abdomen.
The name marsupial is derived from the Latin marsupium, meaning "pouch". This is due to the occurrence of epipubic bones, a pair of bones projecting forward from the pelvis. Marsupials give birth to a live but relatively undeveloped foetus called a joey. When the joey is born it crawls from inside the mother to the pouch.
Vivipary is rare in snakes, but boas and vipers are viviparous, giving birth to live young. [29] Female aphid giving birth. The majority of insects lay eggs but a very few give birth to offspring that are miniature versions of the adult. [18] The aphid has a complex life cycle and during the summer months is able to multiply with great rapidity.
The mammals included are only viviparous (marsupials and placentals) as some mammals, which are monotremes (including platypuses and echidnas) lay their eggs. A marsupial has a short gestation period, typically shorter than placental. For more information on how these estimates were ascertained, see Wikipedia's articles on gestational age.
The name is something of a misnomer, considering that marsupials also nourish their fetuses via a placenta, [1] though for a relatively briefer period, giving birth to less-developed young, which are then nurtured for a period inside the mother's pouch.
Due to the fact that placental mammals and marsupials nourish their developing embryos via the placenta, the ovum in these species does not contain significant amounts of yolk, and the yolk sac in the embryo is relatively small in size, in comparison with both the size of the embryo itself and the size of yolk sac in embryos of comparable developmental age from lower chordates.
After a month of gestation, females give birth to a single baby called a joey. Females can give birth twice a year and produce about 17 joeys during their lifespan. [8] The joey lives in its mother's pouch for six months. Once it leaves the pouch, the joey relies on its mother for milk for two more months and is fully weaned around eight months ...