Jellyfishes have abundant mesoglea helpful in providing buoyancy and in swimming. Polyps have little mesoglea but use the water in their guts as a hydrostatic skeleton. The life cycle of a cnidarian may have a polyp and medusa stage, or it may have just the polyp. The medusa is usually the sexual form with either epidermal or gastrodermal gonads. The zygote develops into a swimming larva called a planula.
Polyps reproduce by asexual budding.
The cilia beat in waves for propulsion. In addition, two long tentacles extend from the body for gathering prey. Although closely related to cnidarians, ctenophorans lack nematocysts and have slightly more advanced tissues. The phylum Platyhelminthes includes the free-living turbellarians as well as the parasitic flukes and tapeworms. Asexual reproduction is by transverse fission.