Sandy beaches and intertidal flats are among the most physically dynamic environments in the sea. The energy expended in the movement of water and sediment is pre-eminent compared to the energy dissipated through food webs. Intermediate beaches are more common worldwide, representing a mixture of characteristics of the two extremes such as medium sand and moderately high waves. Early workers studying intertidal food chains and trophic relationships focused on the relative isolation of beaches and tidal flats from food chains offshore. Reflective sandy beaches are open ecosystems in which food chains receive most of their energy input from either the land or sea, or both. Amphipods and bacteria have a large role to play in other Australian sandy intertidal areas receiving plant detritus. The fate of the material filtering into the sand is therefore an important pathway of carbon and energy flow.