Read the evidence

Kelp is a large alga that uses sunlight to make sugars by photosynthesis. Small sea snails graze on kelp. Fish such as wrasse eat the snails, and larger fish such as snapper may eat smaller fish. Sea urchins also graze on kelp, while a large crustacean eats sea urchins. When organisms die, bacteria and fungi break down their remains and return nutrients to the environment. A marine heatwave can stress kelp and reduce its growth. Food-chain arrows show the direction energy moves: from the food to the eater.

Investigate the ecosystem