Ctenophora, or comb jellies, is an entirely marine phylum with animals that have radial symmetry (like spokes on a wheel) of eight rows of cilia along the length of their body. Instead of the stinging cells of cnidarians, ctenophores have sticky cells on their tentacles or preoral lobes to capture prey. Ctenophores have planktonic larvae. Two classes of ctenophores are class Tentaculata (with tentacles during at least part of life cycle) and class Nuda (with no tentacles). Mniemiopsis leidyi is one of the most abundant zooplankton species in estuaries and nearshore waters where its predation can greatly reduce the abundance of prey such as copepods.

Mniemiopsis leidyi

Comb jelly or sea-walnut (photo by Steven G. Johnson)