Mammals have 2 categories one is marsupial and the other one is placental. Placentals include we mean humans, whales, mice, cats, cows, dogs and an additional 5,500 species. They are actually found everywhere except Antartica. But the reverse is true for Marsupials. There are fewer than 300 known species of marsupials. They are found in Australia, southamerica, and Central America. They mostly include kangaroos, opossums, koalas, wombats, Tasmanian devils, etc.
There are some differences between Marsupials and placentals. They are as follows –
1. placenta – The fundamental difference between Marsupials and placentals is that of possession of placenta. A placenta is an oxygen and nutrient-rich organ that attaches growing embryos of placental mammals to their mother. But on the other hand, Marsupial have no internal placenta. So they absorb nutrients from the yolk of their ovum. Also, the other difference marsupial young ones spend longer time suckling than do placentals.
2. Marsupial Pouch – If there is something different in Marsupials that is pouch in females. But the thing to note is that not all marsupials have pouches but a majority do. Some species have permanent pouches while others may develop it during the reproduction process. Instead of the complex placenta that provide nutrients to babies, marsupials use to provide nutrients and safety.
3. teeth — For most, marsupials they have more teeth than their placental counterparts. While placentals have 4 premolars and 3 molars in the lining of both the upper and lower jaws. But Marsupials have 3 premolars and 4 molars in the same region. Placentals have 2 set teeth — one grown in young age and other in adult but marsupials replace certain teeth.
4. Reproduction — Male Placentals and male marsupials don’t differ much. But females of marsupials than have 2 fully developed reproductive structures including 2 vaginas, two cervices, 2 uteri and 2 fallopian tubes. Marsupial’s vagina is laterally positioned on either side of a ureter, either 1 is capable of being fertilized. At the time of giving birth, 2 vaginae close together and fuse, forming a median vagina also called pseudo-vagina. After marsupial’s birth, the canal reforms until next birth but in some species can remain open permanently.
5.Gestation and rearing differences
Compared to Placental mammals, Marsupials gestate only for a brief period. Young placentals experience, tremendous growth in utero growth and developments. Marsupials do most development after being born.