o Wherever seaweeds grow they have to compete for space, inorganic nutrients and light. They are also in constant danger of being grazed on by gastropods(腹足动物),fsh, sea slugs(海蛤蝓) and sea urchins(海胆) and have some sinister tactics for putting off predators⚫ Wherever seaweeds grow they have to compete for space, inorganic nutrients and light. They are also in constant danger of being grazed on by gastropods（腹足动物）, fish, sea slugs（海蛤蝓） and sea urchins（海胆） and have some sinister tactics for putting off predators