The distal parts of Malpighian tubules in cockroaches open into the coelomic cavity.

Malpighian tubules are excretory structures found in insects, including cockroaches. They play a crucial role in the removal of metabolic wastes from the body. The tubules are long, thin, and coiled structures located in the posterior region of the insect's body.

The opening of the distal parts of Malpighian tubules into the coelomic cavity is an important adaptation for excretion in cockroaches. Here is an explanation of why this is the correct answer:

1. Coelomic cavity:
The coelomic cavity is the main body cavity of an insect, filled with coelomic fluid. It is the space between the body wall and the digestive system. In cockroaches, this cavity is filled with hemolymph, which is the insect equivalent of blood. The coelomic fluid is rich in nutrients and waste products that need to be eliminated from the body.

2. Filtration and reabsorption:
The Malpighian tubules actively remove waste products, such as uric acid, from the hemolymph and transport them to the distal parts of the tubules. The distal parts of the tubules are responsible for the final modification of the filtrate before its elimination. They perform reabsorption of essential ions, water, and nutrients from the filtrate back into the hemolymph.

3. Elimination:
In cockroaches, the distal parts of the Malpighian tubules open directly into the coelomic cavity. This allows the modified filtrate to be released into the coelomic fluid, which is then transported to the hindgut for further processing and elimination. From the hindgut, the waste products are eventually excreted from the body through the anus.

4. Importance of opening into the coelomic cavity:
The opening of the distal parts of the Malpighian tubules into the coelomic cavity ensures efficient elimination of waste products. It allows for direct contact between the modified filtrate and the coelomic fluid, facilitating the exchange of substances. This arrangement also allows for the reabsorption of essential ions and water from the filtrate before it is eliminated.

In conclusion, the distal parts of Malpighian tubules in cockroaches open into the coelomic cavity to ensure efficient excretion and elimination of waste products. This adaptation allows for the modification and reabsorption of essential substances from the filtrate before its release into the coelomic fluid.

The Malpighian tubules are inserted tubular organs in the area between the medium intestine and posterior intestine, which often are free and loose in the body cavity, and in some insects, as already mentioned, the distal end of these tubules found in contact with the wall of the rectum through the perinephric membrane ...