Although the terms reactant and reagent are often used interchangeably, a reactant is more specifically a substance that is consumed in the course of a chemical reaction. Solvents, although they are involved in the reaction, are usually not referred to as reactants.
Animals that live in water, usually called aquatic animals, include fish, cetaceans, certain types of turtles and other reptiles, and amphibians. There are also a number of semiaquatic animals, such as alligators, hippopotamuses and penguins, that depend on and live in water most of the time. Continue Reading.
Certain fish adapted to these changing conditions by gradually developing limbs to crawl with and lungs to breathe with. Such organisms, capable of life both in water and on land, came to be called amphibians, a name that means double life. Amphibians were the first vertebrates (animals with backbones) to live on land.