Sucking and sorting

carp Cyprinus carpio freshwater species california

The common carp (Cyprinus carpio) was one of the first freshwater species to be introduced to California, brought in from Germany to a private pond in 1872. It has now become the most abundant freshwater fish in North America by biomass (McGinnis 2006).

Carp have an interesting way of feeding. When carp expand their buccal cavity and protrude their jaws, they create a suction force like a vacuum cleaner hose. While feeding on insect larvae, small mollusks, crustaceans, and worms they suck up silt, gravel or plants as well. Once their mouth is full, then a bulge in the thick muscular pad that covers the roof of their mouth (palatal protrusion) is used to hold down food particles, while they expel the unwanted silt, gravel and plant matter. In this way they can select what they want to eat and spit out the rest. If only they could design a ‘smart’ vacuum cleaner that would do the same.

Photo source: FISHBIO