Marine life same environmental problems and feeding niches have resulted in similar adaptations. Examples include albatross, penguins, gannets, and auks. In general, marine birds live longer, breed later and have fewer young than terrestrial birds do, but they invest a great deal of time in their young. Most species nest in colonies, which can vary in size from a few dozen birds to millions. Many species are famous for undertaking long annual migrations, crossing the equator or circumnavigating the Earth in some cases. They feed both at the ocean's surface and below it, and even feed on each other. Marine birds can
Flightless bird the lineage. This indicates that the distinctive flightless nature of ratites is the result of convergent evolution. Two key differences between flying and flightless birds are the smaller wing bones of flightless birds and the absent (or greatly reduced) keel on their breastbone. (The keel anchors muscles needed for wing movement.) Adapting to a cursorial lifestyle causes two inverse morphological changes to occur in the skeleto-muscular system: the pectoral apparatus used to power flight is paedorphically reduced while peramorphosis leads to enlargement of the pelvic girdle for running. Repeated selection for cursorial traits across ratites suggests these adaptions comprise a