What are internal waves and where do they form?

Internal wave, a type of gravity wave that occurs on internal surfaces within ocean waters. These surfaces represent strata of rapidly changing water density with increasing depth, and the associated waves are called internal waves.

Explanation:

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.