Final answer:
Barnacles, seaweed, and starfish are located in the intertidal zone, an area that is periodically exposed to the air and submerged in water, where they are adapted to survive the challenging conditions of changing tides and wave impact.
Step-by-step explanation:
Barnacles, seaweed, and starfish can be found in the intertidal zone, which is the area of the ocean that lies between the high and low tide lines. This zone is characterized by its exposure to air and sunlight at low tide while being underwater during high tide. Organisms that inhabit this zone, like sea urchins, mussel shells, and starfish, are adapted to withstand the drying effects of air exposure and the physical impact of waves. These species are often found clinging to rocks or other hard substrates in this dynamic environment, as seen in Kachemak Bay, Alaska.
The neritic zone extends from the intertidal zone to the edge of the continental shelf and is characterized by well-oxygenated water, stable temperatures, and the presence of light, allowing for photosynthesis. This zone supports a variety of sea life including phytoplankton, zooplankton, small fish, and free-floating marine seaweed like Sargassum, which provides habitats for many species.