The Phylum Sarcodina is comprised of protozoan, or sarcodines, that share several characteristics; sarcodines have long, trailing cytoplasm and use unique cytoplasmic feet, or extensions, called pseudopodia to facilitate movement. Sarcodines also use pseudopods to feed, and they reproduce either sexually or asexually, depending on the species.
This phylum includes amoeba and various pathogenic species. These organisms are similar in appearance but have key biological differences at the cellular level. Sarcodines have cells that are either spherical or irregular in shape and form. The pellicles, or envelopes, of their cells are generally soft, transparent and flexible. Some sarcodines have external shells or skeletons and have cytoplasms comprised of ectoplasms and endoplasms, which may have multiple nuclei. These organisms obtain energy by consuming food particles and organic matter. Sarcodines generally eat by trapping food particles and substances with their pseudopods then carrying out digestion in special chambers called food vacuoles. Sarcodines may reproduce sexually or asexually. Sexual reproduction is accomplished through syngamy, which is the fusion of two gametes. Asexual reproduction, contrarily, spawns offspring through cell division. Sarcodines with multiple nuclei undergo cytoplasmic division, which involves the replication of cells and nuclei, in addition to the transfer of genes and traits that occurs during sexual reproduction. These organisms live in virtually every environment and live as individuals or in colonies.