write the ways of excretion in Amoeba, Hydra, Earthworm, Cockroach
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Answer:
Earthworms (annelids) have slightly more evolved excretory structures called nephridia, illustrated in Figure 2b. A pair of nephridia is present on each segment of the earthworm. They are similar to flame cells in that they have a tubule with cilia. Excretion occurs through a pore called the nephridiopore.The excreta of cockroach and other insects is mainly composed of urea and uric acid. After reabsorption, the waste moves to the rectum and is released through anus. Nephridium is an excretory organ present in earthworms.The fluid is excreted through a break in the body wall created as a result of a strong contraction when the gut is distended with fluid. A normal hydra, therefore, must remove excess fluid by contracting and expelling it through its mouth.The contractile vacuole is the excretory organ in the amoeba.