Question

Identify the correct set of mammals that live wholly in water.
A. Whales, seals, dolphins
B. Seals, whales, shark
C. Hippocampus, whale, scoliodon
D. Rohu, shark, Catla

Answer 1

Hint: Among the diverse number and types of organisms on this earth, there are various organisms that have a particular habitat. This could either be land or water or both. They choose their habitat depending on their requirements and body structure.

Complete answer:
On the basis of habitat, organisms are of 3 types-
Terrestrial animals- which live on land only
Aquatic animals- which live in water only
Amphibians- which can survive both on land and in water
The classification on the basis of birth-giving, there are 2 types of animals-
Egg-laying animals- these are the ones which lay eggs which on hatching give rise to new young ones.
Mammals- they are the animals which develop the baby in their womb for some specific time and then deliver their young ones. They feed their child with the milk from the mammary glands.
Option A: Whales, seals, dolphins: Whales, seals, and dolphins are the aquatic animals which give birth to their young ones, thus they are mammals.
Option B: Seals, whales, shark: the shark is not a mammal but they give birth to their young ones. They are an exception to the group whereas seals and whales are mammals.
Option C: Hippocampus, whale, scoliodon: Hippocampus is not a mammal, they have a different structure of the brain from the mammals. The scoliodon is a type of shark thus it is also not a mammal.
Option D: Rohu, shark, Catla: They all three are not mammals. They have different structures than mammals.
So the answer is option A: Whales, seals, dolphins.

Note: Mammals give training to their young ones. They protect them until they are strong enough to protect themselves. Mammals are warm-blooded, which means they cannot change their temperature on their own. They can have hair and fur.