Pomacea bridgesii (The Mystery Snail)The Mystery Snail possesses a kidney also known as the nephridium in its visceral mass. This kidney includes two parts called the posterior chamber and the anterior chamber. The posterior chamber receives the primary urine of the snail. In this chamber, the walls are filled with blood vessels and arteries. The excretory cells on these walls excrete uric acid from the blood into the opening hole of the chamber. The anterior chamber is different because the hole that the uric acid would flow out of is blocked by large and moist mucous membranes called lamina. The tissue on the lamina absorb the ions again from the urine and release them back into the blood. The urine is released from the snail in the renal aperture, which is located in the upper right mantle cavity.
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Tridacna Gigas (The Giant Clam)The Giant Clam is the largest known living mollusk. Similar to the snail, the giant clam also has a nephridium that deals with urine. The nephridium in the giant clam separates the uric acid, salt, toxins, and other wastes from the blood. The nephridium in the giant clam is also located in the visceral mass just below the heart. The uric acid and other wastes that wre absorbed from the blood by the nephridium are excreted out of the clam's mantle cavity.
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Octopus Vulgaris (The Common Octopus)The Common Octopus excretes urine through a pair of distinct kidneys called metanephridium. The tubular structures of these nephridia collect fluids from the coelom, which is a fluid-filled cavity in between the skin of the octopus and the organs. As the fluid passes through these tubes, salts and other contents are exchanged with the body tissue. After passing through these tubes, the nephridia empty the uric acid and the other waste from the fluid into the mantle cavity where it is then excreted out of the body.
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