Help pls i beg

they need to keep water moving over their gills so they seem to have active periods and restful periods instead of undergoing deep  sleep.  they sleep swim

explanation:

ancient india is often called the harappan civilization because one of the ancient cities was called harappa. harappa was just one of 1500 cities in the indus river valley. another well-known city is called mohenjo-daro. historians estimate ancient india to be the biggest of all four early civilizations.