Freshwater organisms live in rivers, lakes, and ponds. They include species like fish, frogs, and insects, which have adapted to low salt concentrations. These organisms play vital roles in their ecosystems, such as maintaining water quality and serving as food for other animals. Marine organisms inhabit oceans and seas, where saltwater dominates. This group includes whales, coral reefs, and plankton. Marine life is diverse and complex, with many species adapted to various depths and conditions. They contribute to global processes, including oxygen production and carbon cycling, making them essential for the planet's health.