Aquatic and Marine Biology

Whales are marine mammals, not fish. They possess mammalian characteristics: they breathe air through lungs, have hair (at some life stage), nurse their young with milk, and are warm-blooded. Their ancestors were land-dwelling mammals.

Four pairs of gills are present in bony fishes.

Rohu - Osteichthyes, Scoliodon - Chondrichthyes, Snake - Reptile, Rhinoceros - Mammalia and Bat - Mammalia.

Crabs, shrimps, lobsters and cyclops are crustaceans.

This is the correct option as fish does not show metamorphosis. 

Birds are warm-blooded (endothermic) organisms because they maintain a constant internal body temperature regardless of the external environment, using metabolic heat production. Fish, frogs, and snakes are all cold-blooded (ectothermic) - their body temperature changes with their surroundings and they rely on external heat sources to regulate their temperature.

Amphibians are uniquely adapted to survive in both aquatic and terrestrial environments. Their life cycle typically begins with water-based larval stages (like tadpoles) and metamorphoses into land-dwelling adults, though they must remain near moist habitats. This dual adaptation distinguishes them from purely terrestrial mammals, aerial birds, or entirely aquatic fish.

Viviparous organisms give birth to live young rather than laying eggs. This is the reproductive strategy used by most mammals including humans. Oviparous organisms lay eggs, while ovoviviparous organisms retain eggs internally that hatch within the body. Omnivorous refers to diet, not reproduction.

Whales are viviparous mammals that give birth to live young after gestation. Dog-fish (sharks) are typically ovoviviparous or viviparous depending on species, but whale is the clearer mammalian example. Ostrich is oviparous (lays eggs), and snakes are mostly oviparous. The question tests knowledge of mammalian reproduction.

This is the correct option. English carp is not a mariculture fish. It is a freshwater culture fish.

Heart of a fish is special because it only has venous blood.

Dolphins breathe through a hole at their top which is called blowhole. The blowhole is the external opening (like a nasal passage) to the lungs. Through its blowhole the dolphin inhales air containing vital oxygen and exhales respiratory wastes including carbon dioxide.

All birds have IgY antibody.

This is the correct option. In crocodile, the heart is four-chambered.

This is the correct option. The organisms of Amphibia class can live in aquatic as well as in terrestrial habitats.