The key difference between placental and marsupial is that placental mammals give birth to fully developed young ones while marsupial mammals give birth to undeveloped young ones and keep them in a special pouch until they mature.
Mammals are a group of animals comprised of warm-blooded, vertebrates that have a backbone, hair or fur and four-chambered hearts. Furthermore, they feed their young ones with milk. Based on the way of developing their babies, there are three major groups of mammals as monotremes, marsupials, and placental mammals. Placental and marsupial are the common mammalian groups including humans and kangaroos, respectively. Moreover, placental and marsupial animals together contain over 85% of all the mammals in the world including the presently most dominant humans. Placental and marsupial mammalian groups have similarities as well as differences. Hence, this article reveals the difference between placental and marsupial in detail.
CONTENTS
1. Overview and Key Difference
2. What are Placentals
3. What are Marsupials
4. Similarities Between Placental and Marsupial
5. Side by Side Comparison – Placental vs Marsupial in Tabular Form
6. Summary
What are Placentals?
Placental mammals are the most diversified group with the highest number of species among all the three mammalian groups. Humans, dogs, elephants, whales, lions, and rhinos are a few examples among more than 4,000 placental mammalian species. Presently, the most dominant form among terrestrial organisms is the placental mammals. They are warm-blooded and have mammalian unique hairs on the skin. Furthermore, they have separately formed anal opening and genitals.
Figure 01: Placental Mammals
Placental mammals give birth to live young followed by a gestation period. During the gestation period, a special structure called placenta nourishes the developing fetus. In other words, the placenta is the physical medium through which the nutrients are transported into the fetus from the mother’s bloodstream. The fetus develops fully and comes out as completely developed young or offspring. In addition, the newborns have hairs in placental mammals. Since this placental phenomenon is only present among placental mammals, they bear great importance. Usually, they possess the most developed brains. In addition, the placental mammals mostly dominate ecological niches.
What are Marsupials?
Marsupial mammals are one of the three major mammalian groups with about almost 500 extant species. Predominantly, marsupials are found in Australia; they are also found in the American continent. Marsupials give birth to an undeveloped young called Joey, following a small gestation period. The Joey comes out of mother, and its development takes place inside an external body pouch that has milk-secreting mammary glands. Joeys do not have hairs on their body when they are newly born. In addition, Joeys are tiny as the size of a jellybean, and they cannot open their eyes; in other words, they are blind at birth.
Figure 02: Marsupial Mammals
Depending on the species and their relative body sizes, the time inside the mother’s pouch varies. But, the completed development has to take place inside the pouch. However, during the short gestation period, there is a placenta between fetus and mother, but it is a very simple structure. One of the noticeable absences in marsupials is the lack of corpus callosum or the bridge of neurons between the left and right hemispheres of the brain. Kangaroo, wallaby, and Tasmanian devil are few of the most well-known marsupials.
What are the Similarities Between Placental and Marsupial?
- Placental and marsupial are two of the three groups of mammals.
- They give birth to young ones and feed with mother’s milk.
- Also, both are vertebrates.
- Furthermore, both are warm-blooded animals too.
- Besides, they have four-chambered hearts.
What is the Difference Between Placental and Marsupial?
Placental and marsupial are two groups of mammals. Placental mammals have a placenta to nourish the fetus while marsupials have a simple placenta that lasts for a short time period. So, this is a difference between placental and marsupial. However, the key difference between placental and marsupial is that the placental mammals give birth to developed young ones while marsupial mammals give birth to undeveloped young ones. Hence, they keep their young ones in a pouch and nourish them till they become mature.
Moreover, placental mammals are more diversified and inhabit a wide range of habitats while marsupial mammals are less diversified and are predominantly found in Australia. So, we can consider this also as a difference between placental and marsupial.
The below infographic on the difference between placental and marsupial provides a detailed comparison.
Summary – Placental vs Marsupial
Among the three groups of mammals, placentals and marsupials are two common groups. They are vertebrates that give birth to young ones and feed them with milk. Placental mammals nourish the fetus via a placenta. Moreover, they give birth to developed young ones. On the other hand, marsupials give birth to undeveloped young ones. Hence, they keep their young ones in a pouch and nourish them until they become mature. Furthermore, they have a simple placenta that lasts for a short time period, unlike placental mammals. Thus, this is a summary of the difference between placentals and marsupials.