Question

What are the functions of the heart and kidney in clams?

Answer 1

Hint: The heart is a bivalved structure in clams and is related to the circulation of blood through the body of the clam and the kidney is there to filter this blood and remove the nitrogenous waste into the water present in the mantle cavity from where it is removed out of the body.

Complete answer:
Clam is a mollusk with a bivalved heart and there found an open blood vascular system. In clams, an organ complex is formed by the heart along with the kidney.
The heart of the clam is enclosed within a pericardial cavity and has a paired auricle or atrium but a single ventricle. In clams and other bivalves, the heart mainly receives and pumps only oxygenated blood called hemolymph.
In clams, paired U-shaped kidneys are present which are connected to the pericardial cavity on one end whereas the opposite end opens in the mantle cavity.
The blood circulating through the clam picks up nitrogen waste or ammonia produced by cells. This is carried to the pericardial cavity where the kidney removes nitrogen waste from the blood and releases it into water present in the mantle cavity from where it moves out of the clam.
The region nearest to the pericardium has glandular walls and it gives way to a non-glandular, wider tube that extends to the urinary opening.
On the auricular wall of the heart, there remains a pericardial gland which is also called Keber's organs where ultrafiltration of hemolymph or oxygenated blood takes place and the accumulated waste is deposited in the pericardial cavity.
From the pericardial cavity, the liquid waste enters the kidneys where reabsorption and secretion of nutrients or ions take place.

Note:
-In clams, the heart is located between the intestines and the anterior and posterior muscles.
-In all mollusks, the primary process in urine production appears to be filtration of the blood. This filtration may take place through the wall of the heart into the pericardium, or from blood vessels that supply the glandular part of the renal gland.
-The urine is mainly made of ammonia and water and is excreted in the mantle cavity from where it is disposed of in the body. In clams, the kidneys also function to remove heavy metals from the blood.