Ctenophora (/ təˈnɒfərə /; sg.: ctenophore / ˈtɛnəfɔːr, ˈtiːnə -/; from Ancient Greek κτείς (kteis) 'comb', and φέρω (pherō) 'to carry') comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide.

Ctenophora is a phylum of exclusively marine invertebrates. Ctenophora means “comb-bearing”. They are commonly known as comb jellies or sea walnuts. The distinguishing feature of the phylum is the presence of comb plates with cilia that are used for locomotion.

Ctenophores (phylum Ctenophora), also known as comb jellies, are marine invertebrates that have eight rows of comb-like cilia on their transparent, gelatinous bodies. They are the largest animal to use cilia for locomotion. Superficially, ctenophores resemble jellyfish, which belong to the phylum Cnidaria.

Ctenophores, variously known as comb jellies, sea gooseberries, sea walnuts, or Venus's girdles, are voracious predators. Unlike cnidarians, with which they share several superficial similarities, they lack stinging cells. Instead, in order to capture prey, ctenophores possess sticky cells called colloblasts.