Phylum Aschelminthes (Gr., askes = cavity ; helmins = worm) is a group of bilaterally symmetrical, unsegmented, and pseudocoelomate animals. They are typically characterized by a cylindrical or thread-like body covered with a tough, flexible cuticle. The phylum includes organisms that are predominantly aquatic or parasitic in nature, such as nematodes (roundworms).
Inside the body of Sponges, the water current flows through a certain system of spaces collectively forming the canal system in sponges.
Phylum Porifera is a group of simple, multicellular, aquatic animals commonly known as sponges. They are characterized by their porous body structure, which allows water to circulate through specialized channels, enabling them to filter-feed by extracting nutrients and oxygen from the water. Most sponges are marine, though some are found in freshwater. Porifera are among the most ancient animal groups, with a simple organization that makes them pivotal to understanding the evolution of multicellular organisms.
Paramecium is commonly known as slipper animalcule. It’s body is slipper shaped measuring about 0.3 mm in length.