The 12,000 species of small, pseudocoelomate wormlike animals which make up the phylum of aschelminthes include a number of lower classes, some of which are themselves often given phylum rank: gastroticha (140 species), rotifera (1,500 species), echinoderida (some taxonomies, 100 species), priapulida (5 species), nematomorpha (250 species), and nematode or roundworms (10,000 species). It is not known how many of these species are endangered, but the principal agents are different forms of water and marine pollution.