Mollusca- Mollusca is the largest phyla of animals, which includes at 50,000 living spices. What makes mollusca distinct is that they all have soft bodies, however some are protected by hard shell. The most known species of mollusca are snails, octopuses, squid, clams, and oysters. They usually live in the ocean or damp habitats. The mollusca are known for having three main body parts: a head-foot (contains the sensory and motor organs), a visceral mass (contains the excretory, digestive, and circulatory structures), and the mantle (used to produce the shell).
Octopus
Octopus and squid are members of the mollusca class Cephalopod. The species in this class have the ability to squirt ink. The cephalopod's excretory systems focus around the pair of nephridia each cephalopod has. Nephridia are tubelike structures that filter the body fluid. The nitrogenous waste moves along the tubes into a bladder-like renal sac. The heart beats pump water in and out to move the waste into sacs, where it is realized through a pore.
Snails
Snails and slugs are in the Gastropoda class of mollusca. Snails and slugs of all different sizes and kinds are included in this class. Like the octopus, the primary organ for snail excretion is the nephridia. It produces a waste product that is pushed out by water through the ureter near the anus. There are also cells in the digestive glands that have a metabolic function, similar to the liver. It helps excrete waste products directly into the digestive system.
Mussels
Mussels, oysters and clams are all part of of the class Bivalvia. The excretory system of the Mussels are almost identical to the excretory system or snails and octopuses and the primary organ is also the nephridia. Blood is forced through the walls and the waste is produced as urine.