Question

Which of the following is an oviparous mammal?
A) Balaenoptera
B) Delphinus
C) Pteropus
D) Ornithorhynchus

Answer 1

Hint: It is also known as Platypus. It is a small carnivorous monotreme marine mammal native to eastern Australia.

Complete Answer:
- The most unusual characteristic of these species is the appearance of mammary glands. Young ones are nourished by their mammary glands.
- They have different types of teeth present. They are animals that are dioecious. Fertilisation is internal and there is direct growth. They are often viviparous i.e. they give birth to young ones.

Now, let us find the solution from the options-
A) Balaenoptera means a blue whale which belongs to the class mammal and it is a viviparous animal.
B) Delphinus means a common dolphin which belongs to the class mammal and it is a viviparous animal.
C) Pteropus means flying fox which belongs to the class mammal and it is a viviparous animal.
There are some exceptions where some mammals are oviparous i.e., they are the egg-laying animals. For example Ornithorynchus is a Platypus which is oviparous.

Thus, the correct answer is option (D) Ornithorhynchus.

Note: Eggs are identified to the vagaries of nature in the case of oviparous animals and also face the hazard of predators. Therefore, to guarantee the survival of the species, a large number of eggs must be laid. The foetus develops to a greater size in the case of viviparous animals that can have higher survival rates after birth. In addition, foetus future requires more sources from the body of the female. Therefore, viviparous animals generate a smaller number of offspring.