Digested nutrients from the
vacuole pass into the
cytoplasm, making the vacuole shrink and moves to the anal pore, where it ruptures to release the waste content to the environment outside of the cell. The cytoproct is used for the
excretion of indigestible debris contained in the food vacuoles. Most
microorganisms possess an anal pore for excretion, usually in the form of an opening on the pellicle to eject out indigestible debris. The opening and closing of the cytoproct resemble a reversible ring of tissue fusion occurring between the inner and outer layers located at the
aboral end. An anal pore is not a permanently visible structure; it appears at the time of defecation and then disappears afterward. In
paramecium, the anal pore is a region of
pellicle that is not covered by ridges and
cilia, and the area has thin pellicles that allow the vacuoles to be merged into the cell surface to be emptied. In
ciliates, the anal cytostomes and cytopyge pore regions are not covered by either ridges or cilia or hard coatings like the other parts of the organism. As a food vacuole approaches the cytoproct region it actually starts to flatten out the surrounding cells, and a thin-membrane vacuole allows it to be combined in the cell wall. Once the vacuole attaches to the plasma membrane of the cell wall, the vacuole is emptied. The waste excreted by the cell can come as a membrane-bound packaged ball, or as a stream of debris behind the organism. Directly after secretion of the waste products, deep
invagination (deep, canyon-like structure that was the vacuole) is still present. About 10 to 30 seconds after secretion, the vacuole detaches, and a new thin plasma membrane is formed. After a minute has gone by the organism's cytoproct is closed up again and the process is ready to be repeated. == In marine animals ==