Organisms adapted to aquatic and terrestrial environments have different adaptations due to environmental constraints. Aquatic organisms adapted to living in water while terrestrial organisms adapted to living on land. Sedentary organisms developed adaptations for staying in one place while mobile organisms adapted for movement. While some traits are considered more advanced, primitive organisms still exist today because different traits allow organisms to thrive in different environments rather than completely replacing each other. Examples include ancestral organisms like jellyfish and derived organisms like birds.