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Sarcodina, the largest phylum (11,500 living species and 33,000 fossil species) of protozoans). It comprises the amebas and related organisms; which are all solitary cells that move and capture food by means of pseudopods, flowing temporary extensions of the cell. Most sarcodines are free living; others are parasitic. One of these parasites is the causative organism of amebic dysentery. With the exception of chloroplasts, sarcodines are identical to the ameboid members of the phylum Chrysophyta. Sarcodines may reproduce asexually by cell division, often without breakdown of the nuclear envelope that is typical in mitosis, or sexually by meiosis and the production of haploid gametes, followed by fusion of gametes and the formation of zygotes.
Sarcodina /Sar·co·di·na/ (-di´nah) a subphylum of protozoa consisting of organisms that alter their body shape and that move about and acquire food either by means of pseudopodia or by protoplasmic flow without producing discrete pseudopodia.
Phylum Sarcodina
The sarcodines are a much more familiar group of protists than the mastigophores. |
The most well-known example of a sarcodine is the famous amoeba. Lacking any rigid structure outside of their cell membrane, sarcodines can freely change their shape and form pseudopodia. Sarcodines can live in both freshwater and marine environments. They can reproduce both asexually and sexually, and they are usually free-living. Like mastigophores, sarcodines use pseudopodia to move and capture food. Although the amoeba is generally thought of as lacking any structure, some have shells, and most other types of sarcodines also have shells. One class of sarcodines, the foraminiferans, possess calcareous shells (they are made of CaCO3). Radiolarians also have shells, but theirs contain silica. While the latter two groups usually live in saltwater environments, the heliozoans live in freshwater. They too can have shells which contain silica. Sarcodines reproduce sexually by
Sarcodina /Sar·co·di·na/ (-di´nah) a subphylum of protozoa consisting of organisms that alter their body shape and that move about and acquire food either by means of pseudopodia or by protoplasmic flow without producing discrete pseudopodia.
Phylum Sarcodina
The sarcodines are a much more familiar group of protists than the mastigophores. |
The most well-known example of a sarcodine is the famous amoeba. Lacking any rigid structure outside of their cell membrane, sarcodines can freely change their shape and form pseudopodia. Sarcodines can live in both freshwater and marine environments. They can reproduce both asexually and sexually, and they are usually free-living. Like mastigophores, sarcodines use pseudopodia to move and capture food. Although the amoeba is generally thought of as lacking any structure, some have shells, and most other types of sarcodines also have shells. One class of sarcodines, the foraminiferans, possess calcareous shells (they are made of CaCO3). Radiolarians also have shells, but theirs contain silica. While the latter two groups usually live in saltwater environments, the heliozoans live in freshwater. They too can have shells which contain silica. Sarcodines reproduce sexually by