Question

Body having meshwork of cells, internal cavities lined with food filtering flagellated cells and indirect development are the characteristics of phylum
(a) Coelenterata
(b) Porifera
(c) Mollusca
(d) Protozoa

Answer 1

Hint: Studies found that 5,000 living species are classified in this phylum approximately. They are composed of three distinct groups, the Hexactinellida, the Demospongia, and the Calcarea. They are sessile and sedentary with body shape is vase or cylinder-like, asymmetrical, or radially symmetrical which grows like a tree. The surface of the body is perforated by numerous pores called the Ostia through which water enters the body and one or more large openings, the oscula by which the water exists.

Complete step by step answer:
A skeleton in zoology can be defined as any fairly rigid structure of an animal, irrespective of whether it has joints and irrespective of whether it is biomineralized. In most sponges, the mesohyl functions as an endoskeleton and is the only skeleton in soft sponges that encrust hard surfaces such as rocks. These mesohyls are mostly stiffened by mineral spicule and spongin fibers or both. These spicules are made of silica or calcium carbonate and they vary in shape from simple rods to 3D stars with up to six rays. Organic matter forms a thin layer with choanocyte chambers in pits in the mineral as sclerosponges ("hard sponges") are seen containing massive calcium carbonate exoskeletons. Pinacocytes secrets these exoskeletons that form the animals' skins. When some sponges are only a few weeks old, they start sexual reproduction, while others wait until they are several years old. These creatures are characterized by the possession of a unique feeding system among animals. They don’t possess any mouths; in their outer walls, they have tiny pores instead through which water is drawn. These tiny little cells in the sponge walls filter the required things from the water as the water is pumped through the body and out other larger openings. The beating of flagella drove the flow of water(unidirectional) which lined the surface of chambers connected by a series of canals. It is seen that the cells of sponge perform a variety of bodily functions and they appear to be more independent of each other than are the cells of other animals.

So, the correct answer is, ‘Porifera’.

Additional information:
1) Among all of them, some calcified demosponges grow by only 0.2 mm (0.0079 in) per year, and if this rate remains constant, those specimens of 1 m (3.3 ft) wide must be about 5,000 years old.
2) All porifera are aquatic but mostly marine except one family Spongillidae which lives in freshwater.
3) All sponges are hermaphrodite and they fertilize internally but cross-fertilization can also occur. Development in sponges occurs indirectly through a free-swimming ciliated larva called amphiblastula or parenchyma.
4) In a sponge, each of the cells that make up the body is independent, even when a sponge “eats,” each of the cells works on its own to digest the food.
5) Sponges have no organs or tissue on their bodies but this multicellular organism has a cellular level of body organization.

Note: A report described the use of sponges as a tool in 1997 by bottlenose dolphins in Shark Bay in Western Australia. Presumably, they said that a dolphin will attach a marine sponge to its rostrum, which is then used for protection while searching for food in the sandy sea bottom. This sea creature shows medicinal potential, due to their microbial symbionts of chemicals that may be used to control viruses, bacteria, tumors, and fungi. They Lack any kind of protective shell but sponges have evolved to synthesize a variety of unusual compounds. Oxylipins is one such class of oxidized fatty acid derivatives and members of this family have been found to have anti-cancer, anti-bacterial, and anti-fungal properties. One example is that plakoridine A is isolated from the Okinawan plakortis sponges, which has shown potential as a cytotoxic to murine lymphoma cells.