Which aquatic organism is classified under the category of invertebrate filter feeders?

Clams are classified as invertebrate filter feeders due to their unique feeding process. They possess a specialized structure known as the siphon, which allows them to draw in water. As water passes through the gills, food particles such as algae, plankton, and detritus are filtered out and trapped in mucous before being transported to the mouth. This feeding strategy is efficient for obtaining nutrients from their environment while remaining stationary in aquatic habitats. The absence of a backbone reinforces their classification as invertebrates.

In contrast, organisms like catfish, frogs, and salmon are vertebrates, possessing a backbone. They have different feeding adaptations and do not operate as filter feeders, making clams the correct choice for this category. Understanding these distinctions helps in recognizing the ecological roles of various aquatic organisms in freshwater ecosystems.