Submerged plants are aquatic plants that grow entirely underwater. They play a crucial role in aquatic ecosystems by providing oxygen through photosynthesis and serving as habitat for various aquatic organisms. Common examples include eelgrass and hornwort, which can be found in freshwater and saltwater environments. These plants help stabilize sediments and improve water quality by absorbing nutrients. They also provide food and shelter for fish and invertebrates, contributing to the overall health of aquatic habitats. Submerged plants are essential for maintaining biodiversity and supporting the food web in their ecosystems.