Marine organisms in the cosmopolitan category are those that are commonly found or invasive species. Invasive species often harm the environment by competing with native species. Commonly found organisms are usually located throughout the ocean and generally benefit by playing a large role in the food chain. Organisms can benefit the environment in other ways for example polychaete worms help to decompose organic matter in the soil. Adaptations, such as the rotifer’s ability to survive with little water, are reasons why certain organisms are more commonly found than others. Overall, the cosmopolitan category has many reasons why organisms are invasive and commonly found in the ocean and either have positive or negative effects on the environment.
