Ctenophores (from the Greek kteis, "comb," and fera, "to carry") are marine, gelatinous, often translucent animals commonly called "comb jellies." Despite the similar name, they are not closely related to jellyfish, which are exclusively found in the phylum Cnidaria. Lacking the characteristic stinging cells (cnidocytes) which give cnidarians their name, they use a wide variety of unusual but highly efficient feeding methods to capture prey, as well as filter-feeding. Many ctenophores bear two tentillae, which allow them to ensnare prey using adhesive cells called colloblasts. Also unlike cnidarians is the presence of paired anal pores located opposite of the mouth; with some ctenophores bearing anal pores that, bizarrely, close off completely when not in use, a type of temporary orifice referred to as a transient anus.
The body of a ctenophore is propelled through the water by eight rows of tightly packed ciliated plates called comb rows, which readily refract light, leading to an often bedazzling rainbow or iridescent effect across each row.
Many ctenophores are simultaneous hermaphrodites, with only one known species recorded to be gonochoric (bearing separate sexes among individuals).

Ctenophores are thought to be only distantly related to all other animal life, and the second oldest diverging member of the animal family tree, with sea sponges having diverged even earlier. Being so early among the animal family tree, ctenophores long predate the cnidarians they only passingly resemble, with a sparse fossil record extending back to the early Ediacaran period, 635-541 million years ago, though being soft bodied, they do not fossilise well.