Plants do not eat. They make their own food through photosynthesis. The same is true of underwater plants. They use the carbon dioxide given off by living things through cellular respiration and carbon dioxide that dissolves into the water from the air, and the energy from sunlight that penetrates the water to make their own food through photosynthesis. Plants that live in deeper water have many different photosynthetic pigments available to them besides just chlorophyll.
MASHROOM
plants under water do the exact same thing as plants grown on land some under water plants suck there prey in and eat them
other fish under water plants
Pouch snails eat things under water such as algae and underwater plants.
Dugongs and manatees eat fleshy roots and leafs from underwater plants.
Some fish eat water plants. Manatees, or sea cows, also eat water plants. Humans also eat some sea plants.
they get it from the things they eat
Under water newts eat worms.
Organisms that eat water plants and duckweed called omnivores.
Since the Sea cow lives under water it eats aquatic plants, and its a total herbivore.
An omnivore eats meat and plants, so an omnivore fish would eat all kinds of underwater plants, it would also eat smaller animals that live under water (e.g. other fish)
Dolpins are at like about the Middle of the food chainand they eat squid and fish and the squid eat little fish and the plants that live under the water