Доклад по теме"Жизнь под водой"

Water is an essential component of life on our planet. In the beginning of time life itself originated in water. The World ocean which covers two thirds of the Earth's surfacre can be called home for the millions of bacteria, fish and seaweed, from the smallest organisms to giant mammals. All of them breathe oxygen dissolved in water, like terrestrial creatures. Underwater life is similar to living in a multi-storey building, where each floor is occupied by its inhabitants.