AP BIOLOGY

Detailed explanation-1: -Organisms belonging to Phylum Mollusca excrete with the help of metanephridia . In some molluscs, the organ of Bojanus is the metanephridia which act as a kidney and performs excretion.

Detailed explanation-2: -Mollusks have a coelom and a complete digestive system. Their excretory system consists of tube-shaped organs called nephridia (see Figure above). The organs filter waste from body fluids and release the waste into the coelom.

Detailed explanation-3: -The vast majority of mollusks are aquatic and excrete nitrogen in the form of ammonia. In octopuses, however, nitrogen is excreted as ammonium chloride, which is quite strongly concentrated in the urine. Terrestrial snails and slugs excrete uric acid but may also excrete ammonia when living in moist surroundings.

Detailed explanation-4: -Typically in molluscs excretion of purines and other waste products and abstraction of valuable solutes are shared equally by the paired bilaterally symmetrical kidneys, different regions of these coelomoducts being specialized for specific functions.

Detailed explanation-5: -This particularly concerns the molluscan kidneys, which are mostly regarded as being derived convergently to the metanephridia of e.g. annelids because of different ontogenetic origin.