Marine biology is the scientific study of marine life, organisms in the sea. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy. Marine biology, the science that deals with animals and plants that live in the sea. It also deals with air-borne and terrestrial organisms that depend directly upon bodies of salt water for food and other necessities of life. In the broadest sense it attempts to describe all vital phenomena pertaining to the myriads of living things that dwell in the vast oceans of the world. Some of its specialized branches concern natural history, taxonomy, embryology, morphology, physiology, ecology, and geographical distribution. Marine biology is closely related to the science of oceanography because of the relationship of the physical features of the oceans to the living organisms that dwell in them. It aids in the understanding of marine geology through the study of those organisms that contribute their skeletal remains to the floors of the oceans or that elaborate the vast coral reefs of the tropic seas.