Answer:
1.Hermit crabs are omnivorous scavengers, eating microscopic mussels and clams, bits of dead animals, and macroalgae. These crustaceans have been misnamed for two reasons: First, they're not true crabs, like blue crabs, in that they don't have a uniformly hard exoskeleton and can't grow their own shells.
2.Limpets eat by grazing on algae found on rock surfaces. They scrape films of algae from the rock with a radula, a ribbon-like tongue with rows of teeth. Limpets move by rippling the muscles of their foot in a wave-like motion.
3.Phytoplankton and algae form the bases of aquatic food webs. They are eaten by primary consumers like zooplankton, small fish, and crustaceans. Primary consumers are in turn eaten by fish, small sharks, corals, and baleen whales.
4 Sea urchins will eat just about anything that floats by. Its sharp teeth can scrape algae off rocks, and grind up plankton, kelp, periwinkles, and sometimes even barnacles and mussels. Sea urchins are sought out as food by birds, sea stars, cod, lobsters, and foxes.
