Essay On Phylum Porifera

1.0 INTRODUCTION Figure 1 External structure of sponges

Phylum Porifera which is mainly occupied by sponges are considered to be the most primitive phylum in kingdom Animalia. Their structure and appearance are somehow look similar to polyps from phylum Cnidarian and sea squirts from subphylum Urochordata where they too aquatic. The first elements that will be used to classify animals into evolutionary hierarchy are their body plan and the presence of true tissue. From there itself sponges failed to exhibit the advance or the common characteristics of animals even though all the living organisms are believed to be arose from a single common ancestral protist cell.

Sponges are organisms that appear in small (few millimeters) to large (2 meters or more) sizes on the sea and ocean floors. Like corals (cnidarians) sponges are brightly colored by the pigments found in the dermal

As for true tissue, arguments are carried out by different parties and scientists where some do agree that sponges have true tissues that specialized to perform particular function and some are not. As the basic criteria itself failed to classify the sponges into advanced phyla, other characteristics shown by advance organisms are totally been neglected off Porifera.

Sponges’ bodies are fully designed with ample of tiny pores that make them efficient filter feeders. The filter feeding system is really fundamental for the organisms under this phylum as they possess an inactive lifestyle by being sessile during adult stage. They fully dependent on the water current created by continuously beating flagellated choanocytes that decorating the internal wall of their body. The water current that aid in the water flow through the porocytes, that make up the pores, and out via osculum, a large opening of sponges, not only help in feeding but also in excretion and