What are marsupials characterized by?

Answer 1

Most marsupials are characterised by a pouch, but not all of them are. The numbat, for example, is a marsupial without a pouch.

However, all marsupials are characterised by the fact that the young are born extremely undeveloped, and must find their way to the mother's teat which then swells in the young joey's mouth, attaching it firmly in place while it continues its development - either inside a pouch, or clasping the mother's underbelly.

Female marsupials have two vaginas, or what are called paired lateral vaginae. These are for the purpose of transporting the sperm to the womb, but there is a midline pseudovaginal canal for actually giving birth. As well as two vaginas and two uteruses, female marsupials have two fallopian tubes and two cervixes. Most male marsupials, with the exception of the largest species, the Red Kangaroo, Eastern Grey and Western Grey Kangaroos, have a "bifurcated" or two-pronged penis to accommodate the females' two vaginas.

Answer 2

Marsupials are mammals with pouches in which they rear their young. Other mammals do not have this feature. Marsupial young are characterised by being extremely small and undeveloped at birth. At birth, they take a long, arduous journey from the birth canal, driven purely by instinct, grabbing hold of the mother marsupial's fur which she has cleaned and made easier to traverse with saliva, to reach the pouch. Upon reaching the pouch, they latch onto a teat which swells in their mouth to prevent them from being accidentally dislodged during the mother's movements. There they stay for months, to complete their development.

Not all marsupials have pouches, e.g. the numbat has a mere flap of skin, but in animals where the pouch is absent, the young are still born undeveloped, and they cling by instinct to the underside of their mother's belly, still firmly attached to teats which swell in their mouths.

Female marsupials have two vaginas, or what are called paired lateral vaginae. These are for the purpose of transporting the sperm to the womb, but there is a midline pseudovaginal canal for actually giving birth. As well as two vaginas and two uteruses, female marsupials have two fallopian tubes and two cervixes. Most male marsupials, with the exception of the largest species, the Red Kangaroo, Eastern Grey and Western Grey Kangaroos, have a two-pronged penis to accommodate the females' two vaginas.