Though comb jellies are, for the most part, of small size, at least one species, the , may attain a length of more tha.... plankton ctenophor

Apart from a few creeping and parasitic species, ctenophores float freely suspended in the water. Except for one parasitic species, all of them are carnivorous, eating myriads of small planktonic animals. When abundant in a region, ctenophores consume most of the young of fish, larval crabs, clams, and oysters, as well as copepods and other planktonic animals that would otherwise serve as food for such commercial fish as sardines and herring.