Aquatic and Marine Biology

Reason: Peneaus monodon is a type of marine (in sea) prawn. Inland fisheries include freshwater resources like canals, ponds, reservoirs and rivers. Brackish water resources are the ones where sea-water and fresh water mix together such as estuaries and lagoons. 

Reason: Marine fisheries include deep seas and coastline. In India, it includes 7500 km coastline and the deep seas beyond it. Popular marine fish varieties include pomphret, tuna and sardine, while freshwater fishes inhabit rivers and lakes. For example, catla is a freshwater fish.

Reason: The practice of growing four to five fish species in a single fish pond is known as composite fish culture. In such systems, these species are selected so that there does not exist any competition for food among them having different types of food habits. E.g. catlas are surface feeders, rohus feed in the middle zone of the pond, mrigals and common carps are bottom feeders and grass carps feed on the weeds. These species when together, can use all the food in the pond without competing with one another. This increases the fish yield from the pond.

Reason: Catlas serve as surface feeders in a composite fish culture. The practice of growing four to five fish species in a single fish pond is known as composite fish culture. In such systems, these species are selected so that there does not exist any competition for food among them having different types of food habits, e.g. catlas are surface feeders, rohus feed in the middle zone of the pond, mrigals and common carps are bottom feeders, and grass carps feed on the weeds. These species, when together, can use all the food in the pond without competing with one another. This increases the fish yield from the pond. 

 Reason: The practice of growing four to five fish species in a single fish pond is known as composite fish culture. In such systems, these species are selected so that there does not exist any competition for food among them having different types of food habits. E.g. catlas are surface feeders, rohus feed in the middle zone of the pond, mrigals and common carps are bottom feeders and grass carps feed on the weeds. These species when together can use all the food in the pond without competing with one another. This increases the fish yield from the pond. One problem with such composite fish culture is that many of these fish breed only during monsoon. Even if fish seed is collected from the wild, it can be mixed with that of other species as well. So, a major problem in fish farming is the lack of availability of good quality seed. To overcome this problem, ways have been worked out to breed these fish in ponds using hormonal stimulation. This has ensured the supply of pure fish seed in desired quantities. Change in food habits will not work as already the fishes selected for composite farming have different food habits. Therefore, improving their feed will also not help in getting pure fish seed. Satellites and echo-sounders are used to locate large school of fish in the open sea.

Most fish are ammonotelic, meaning they excrete nitrogen primarily as ammonia. This is because they live in water and can easily dilute and eliminate toxic ammonia through their gills. Ammonia requires minimal energy to produce. Terrestrial organisms convert ammonia to less toxic urea or uric acid, which need less water for elimination but require more energy to synthesize.

Chiton, Pila (apple snail), and Unio (freshwater mussel) are all molluscs - they belong to the phylum Mollusca. Prawn, however, is an arthropod (class Crustacea). Arthropods have jointed legs and an exoskeleton, while molluscs have a muscular foot and soft body. The prawn is the odd one out because it belongs to a completely different phylum.

Dogfish are small sharks, which belong to the class Pisces (fish). More specifically, they are cartilaginous fish (Chondrichthyes). They are not mammals (which have hair and mammary glands), reptiles (which have scales and lay eggs on land), or amphibians (which typically have metamorphic life cycles). As fish, they have gills, fins, and live entirely in water.

Pisces (fish) are oviparous, meaning they lay eggs that develop and hatch outside the body. Most fish species produce large numbers of eggs that are fertilized externally, with the embryos developing within the eggs in water. This is in contrast to viviparous animals that give birth to live young, or saprophytes/parasites which describe nutritional modes not reproductive strategies.

Amphibians are uniquely adapted to live both on land and in water during their life cycle. Most amphibians have aquatic larval stages (like tadpoles) and terrestrial adult stages, requiring moist skin and specialized respiratory methods for both environments. This dual lifestyle distinguishes them from purely aquatic fish, purely terrestrial birds and mammals, or animals confined to one habitat.

Pisces (fish) are cold-blooded animals with streamlined bodies and gills for aquatic respiration. Amphibians have both aquatic and terrestrial life stages, reptiles have lungs, and birds are warm-blooded.

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.