Aquatic and Marine Biology

This is a classic riddle playing on the phrase 'man-eating shark' - Jennifer wasn't afraid because it was a shark that eats men, not humans (or she's a man). The humor comes from taking the literal meaning of a commonly used phrase. 'Shark had no teeth' misses the wordplay, 'shark was scared' is illogical, and 'I don't know' is a surrender.

They are free-floating, aquatic plants, e.g. algae, protists, and cyanobacteria.

It is a green alga. It is commonly known as sea grape. It is a common seaweed.

 Fishes do not have ear ossicles.

Bony fishes are ammonotelic.

Scoliodon has cartilaginous endoskeleton and placoid scales.

Physically the brain of fish does not have a hippocampus region which is found in higher order vertebrae animals. The hippocampus is the part of the brain that is involved in memory forming, organising, and storing.

This is the correct option because mussels are farmed in sea water. Composite fish farming includes grass carp, which feeds on weeds. These species can co-exist in a single pond with the others, and thus, increase the yield of fish from the pond. This is the correct option because mussels are farmed in sea water.

Daula or ophiocephalaus striatus is a fresh water food fish.

It is the fish that can feed on the weeds.

Crap culture is also called composite culture. Sewage fed fish culture is very popular and so is fish culture in bundhs. Integrated fish culture is also a part of the different fish cultures in practice. Thus, this answer is correct.

Sea otters (Enhydra lutris) are commonly cited as an example of a keystone species because they limit the density of sea urchins.

Reason: Oysters are cultivated for the pearls they make. Oysters have long been valued for the precious pearls that develop in them. Some oysters are also eaten as food. But shell and teeth are not useful in them. 

Reason: Mussels and oysters thrive in marine (in sea) water habitat. 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: The practice of culturing marine fish stock is known as mariculture. Apiculture is the practice of rearing and breeding bees. Aquaculture is the farming of freshwater and saltwater organisms such as fishes and aquatic plants. It is also called aqua farming. Hydroculture is growing of plants in a media that allows the distribution of water and nutrients through capillary action. Clay can be used to anchor plants. It generally involves growth of plants without the use of soil.