A phylum of marine invertebrates that contains the comb jellies (e.g. Pleurobrachia) and sea gooseberries. They typically have spherical or oval bodies, although some are ribbon shaped or are equipped with tentacles. The body wall encloses a gastrovascular cavity that communicates with the exterior via a mouth and several anal pores. They possess tentacles armed with lasso cells, for catching prey, and many hundreds of thousands of cilia, which are fused at their bases and grouped together into longitudinal rows (comb plates or ctenes). The beating of the cilia enables these animals to swim among the plankton. The ctenophores were formerly believed to be close relatives of the cnidaria, but molecular systematics now places them as the sister group of all other animals apart from sponges.