Water lilies, belonging to the family Nymphaeaceae, form vast floating communities that are a fundamental part of freshwater ecosystems across the globe. These aquatic plants, characterized by their broad pads and submerged structures, represent a significant food source for a diverse array of animal life. The plant’s various components, including the starchy underground rhizomes, tender surface leaves, and nutrient-dense seeds, are consumed by herbivores of nearly every size.
Large Mammals and Rodents
Large mammals are among the most impactful consumers of water lilies, often seeking the plants for their high mineral content and concentrated carbohydrates. The North American Moose (Alces alces) is known for wading deep into ponds and lakes to feed on aquatic vegetation, sometimes submerging its entire head. Moose rely on these plants, including water lilies, to obtain necessary sodium, which is often scarce in their terrestrial diet, particularly during the summer months. A single moose can consume significant quantities of these plants in a day, pulling up the entire stalks and pads.
Semi-aquatic rodents, such as the Beaver (Castor species) and the Muskrat (Ondatra zibethicus), also heavily utilize water lilies. Beavers, though known for eating woody bark, switch to a diet rich in herbaceous aquatic plants during the warmer seasons. They actively seek out and excavate the nutrient-rich rhizomes (underground tubers) of water lilies, sometimes storing these starchy roots near their lodges for winter consumption.
Muskrats similarly feed on the stems, leaves, and roots of water lilies. The rhizomes are a preferred part of their diet, especially when other forage is less available. These rodents often create feeding platforms where they bring the harvested plant material to eat.
Aquatic Birds and Waterfowl
Waterfowl represent another major group of water lily consumers, with different species specializing in distinct parts of the plant based on their foraging anatomy. Swans, such as the Mute Swan (Cygnus olor) and the Trumpeter Swan (Cygnus buccinator), are powerful herbivores that use their long necks to reach deep below the surface. They uproot and consume the submerged stems, roots, and tubers of the plants, which provide a substantial source of energy.
Other waterfowl, including various species of Ducks and Geese, tend to focus on the surface or near-surface components of the plants. Ducks often dabble on the water’s surface, consuming the small seeds shed by the lilies, as well as the tender new shoots. Coots and Geese frequently graze on the floating leaves and young flower buds, contributing to the ragged appearance of lily pads in heavily populated areas.
Insect and Invertebrate Grazers
The smallest but most specialized herbivores in the water lily ecosystem are the insects and invertebrates, which often cause distinctive patterns of damage. The Water Lily Beetle (Galerucella nymphaeae) is a primary example, with both the adult beetle and its larvae feeding on the leaves. The adults chew small holes into the upper leaf surface, while the larvae graze away the top layer of tissue, causing the leaf to lose buoyancy and eventually rot.
The aquatic caterpillar of the Brown China Mark Moth (Elophila nymphaeata) is another specialized consumer. This larva cuts sections of the lily pad to create a protective case, or “boat,” in which it lives while feeding on the leaf tissue.
Aquatic snails, such as the Great Pond Snail, also graze on the pads. They typically prefer to consume algae and decaying matter, but they will also chew on healthy leaves, leaving behind noticeable holes.