A subphylum of Protozoa. Sarcomastigophora replaces Rhizoflagellata for those protozoa that possess flagella or pseudopodia or both, according to a classification set up by an international committee of the Society of Protozoologists. Included organisms have a single type of nucleus, except the developmental stages of some Foraminiferida. Sexuality, if present, is syngamy, the fusion of two gametes. Spores typically are not formed. Flagella may be permanent or transient or confined to a certain stage in the life history; this is true also of pseudopodia. Both flagella and pseudopodia may be present at the same time.