A cytostome or cell mouth is a part of a cell specialized for phagocytosis, usually in the form of a microtubule-supported funnel or groove. Food is directed into the cytostome, and sealed into vacuoles. Only certain groups of protozoa, such as the ciliates and excavates, have cytostomes. In others, and in cells from multicellular organisms, phagocytosis takes place at any point on the cell or feeding takes place by absorption. Phagocytosis (literally, cell eating) is a form of endocytosis where large particles are enveloped by the cell membrane of a (usually larger) cell and internalized to form a phagosome, or food vacuole. ... Microtubules are protein structures found within cells. ... Vacuoles are large membrane-bound compartments within some eukaryotic cells where they serve a variety of different functions: capturing food materials or unwanted structural debris surrounding the cell, sequestering materials that might be toxic to the cell, maintaining fluid balance (called turgor) within the cell, exporting unwanted substances from the... Protozoa (in Greek protos = first and zoon = animal) are single-celled creatures with nuclei that show some characteristics usually associated with animals, most notably mobility and heterotrophy. ... Classes & Subclasses Class Karyorelictea Class Heterotrichea (e. ... This article is about the protist group called excavates. ...