Grades 3–5 · Organisms
How does a mussel gather food from passing water?
A mussel can feed while staying in one place. Water carries tiny food particles past it, but the mussel is not simply waiting for particles to fall into its mouth. Inside its partly open shell, tiny moving structures help bring water and food together.
In the diagramMoving cilia bring water and foodWater entersWater leavesGill surfaceToward mouth6 particles2 pass onwardCilia and mucuscarry particles4 capturedthen sortingInvented counts: captured does not mean eaten
Hairlike cilia on the gills beat in coordinated patterns. Their movement drives water into the body cavity, across the gills and outward again. These gills exchange gases as well as helping the animal feed.
Some suspended particles are captured at the gill surfaces. Mucus and further ciliary movement help transport the captured material toward folds beside the mouth called labial palps. Material can be sorted there: some goes to the mouth, while some is rejected rather than swallowed.
The illustration follows six invented particles, four captured and two passing onward. Capturing is not the same as digesting. Real capture and feeding depend on the particles, water conditions and the animal’s activity; a mussel does not remove every substance in water.
About this explanation
Starting knowledge: Understand that water can carry small suspended particles.
Sources
- NOAA Fishery Bulletin — Food and Feeding in Fresh-water Mussels
- Meseck and colleagues, Ecological Indicators / NOAA — Physiological feeding rates and cilia suppression in blue mussels with increased levels of dissolved carbon dioxide