Question

Amongst the following mammals which of the following is a monotreme?
A) Macropus (Kangaroo)
B) Ornithorhynchus (Platypus)
C) Balaenoptera (Blue whale)
D) Elephas (Elephant)

Answer 1

Hint: Along with placentals and marsupials, monotremes are one of the three major categories of living mammals. When compared to more common mammalian kinds, monotremes have anatomical differences in their brains, jaws, digestive tract, reproductive tract, and other body parts.

Complete answer:
Macropus (Kangaroo): A marsupial is a mammal with a pouch that it uses to carry its babies. Marsupials give birth to their young earlier than placental mammals. Because they have to climb to the mother's nipples to feed, they have exceptionally strong limbs. The koala and kangaroo are examples of marsupials.

Ornithorhynchus (Platypus): A monotreme is an egg-laying animal. This implies that they do not have children in order to live a long life. They also hold the eggs within for a longer period of time to ensure that the egg gets enough nutrients. A platypus or echidna is an example of a monotreme.

Balaenoptera (Blue whale) and Elephas (Elephant): A placental mammal is a mammal that is born fully mature after being nourished in the mother's uterus. Whales, cats, dogs, and humans, to name a few, are among the members of this diverse group.

- Platypus is a mammal that lays eggs. It hatched its eggs in a grass and leaf nest.
- The kangaroo is a gregarious marsupial mammal.
- The young of the blue whale and elephant is born. That is they have a placenta.

Therefore the correct answer is option ‘B’.

Note: Platypus is described as the "connecting link" between reptiles and mammals since it possesses both mammalian and reptilian characteristics. Hair, mammary glands, and a diaphragm are all mammalian characteristics. It's oviparous, which means it lays eggs like a reptile.