Question

Which of the following animals give birth to live ones?
(a)Ornithorhynchus and Echidna
(b)Macropus and Pteropus
(c)Balaenoptera and Homo sapiens
(d)Both (b) and (c)

Answer 1

Hint: Some animals give birth to live ones, while some give birth to eggs which later hatch. The animals that give live birth are generally mammals, while those that lay eggs or similar structures are generally fish, birds, reptiles, insects, and amphibians.

Complete answer:
- Animals that give birth to live young are viviparous. The young ones develop inside one of the parent’s bodies.
- Mammals are a class of animals that are known to give birth to live animals, with a few exceptions. Out of the given options, the viviparous mammals are Macropus, Pteropus, Balaenoptera, and Homo sapiens.
- Viviparous eggs do not contain enough yolk for the embryo unlike their oviparous counterparts, hence the offspring develops inside the parent’s body and derives nutrition and protection from them. Oviparous creatures lay an egg which encases the embryo. The composition of the egg structure depends on the environment and the animal.

Additional Information: - Ornithorhynchus is the platypus. It is one of the few egg-laying mammals. Hence, they are oviparous.
- Echidna or spiny anteater is an egg-laying mammal as well, hence they are oviparous.
- Macropus is the genus of kangaroos, wallaroos, and wallabies. They are marsupials and give birth to live ones.
- Pteropus are fruit foxes or flying bats, which are mammals and belong to the megabats suborder. They give birth to live offspring.
- Balaenoptera are baleen whales and they are mammals and viviparous.
- Homo sapiens are human beings and are mammals and viviparous.

So, the correct answer is ‘Both (b) and (c)'.

Note: - An ‘in-between’ stage of the two exists known as ovovivipary which exists in some reptiles.
- Examples of oviparous animals are most fish, amphibians, reptiles, birds, monotremes, insects, molluscs, and arachnids.
- Examples of viviparous animals are humans and other mammals, higher sharks, and amphibians.