The ocean covers about 70% of earth’s surface and is great reservoir of life. The study which deals with the marine and coastal habitat and its organisms is known as Marine and Coastal ecology. Ecology is the scientific discipline of understanding interactions between living organisms and their environment. Ecology is also the study of ecosystems with their network of complex interactions and mutual relationships between plants, animals, microorganisms and their surrounding environment. The application of ecological knowledge spans conservation and protection of animals and plants in their natural environment, the restoration of natural habitats, and management of natural resources. The current research trend includes ecology of invasive species, the link between ecology and the physical properties of the water and the marine environment, taxonomy and biodiversity, as well as the effects of human activities and climate change.