Problem 1

Background and context

Sponges usually do not show true tissue- level of organization and do not have a large number of functional tissues, that are made up of different cell types specialized for distinct functions such as pinacocytes. Pinacocytes are epithelium-like cells and form the outermost covering of the body, called a pinacoderm, that serves a protective function similar to the epidermis. Pinacoderm scattered among all area of Ostia allows the entry of water into the body of the sponge.