Membranipora membranacea

Membranipora membranacea ("lacy-crust bryozoan") is a marine ectoproctan species (formerly classified as a bryozoa) that can be found from Alaska to the California coast. This species does not have ovicells or avicularia, which are common to most bryozoans.

M. membranacea usually have zooecium (tissue) surrounding a blind-ended gut and have a opening on the top of the tissue called an operculum, which acts as both anus and mouth. Surrounding this operculum are lophophores, which are tentacles that are used to catch nutrients floating in the ocean. This species does not have a skeletal system and their muscles support the whole(hydrostatic skeletal system) of the body.

M. membranacea feed on sea plankton and parasites using their tentacles to catch them. Since they are too small to have a separate respiratory system, they get the oxygen they need from seawater by diffusion. When mature, they produce statoblasts, which are like babies; the statoblasts have hooks enabling them to cling to a surface and start to grow in a new colony. Statoblasts can survive in dry and cold environments, unlike adult-stage individuals, and they form new colonies when they meet a favorable environment.

Factors that hinder M. membranacea growth include changes in pH, plankton overload, and marine pollution.