Cnidarians include corals, and corals provide shelter for millions of ocean species.
Not only that, but most species of coral polyps also house algae in their cells, thereby pretty much functioning as plants during the day. The algae photosynthesise and give off nutrition to the coral polyps. This is why many corals are shaped like plants - to catch as much light as they can for the algae, in the same way as plants do. By photosynthesizing, they also capture CO2 like plants do. They're underwater rainforests with the same capacities and biodiversity. Read more: http://www.answers.com/Q/How_do_cnidarians_benefit_the_environment#ixzz3Ym14qtMb |