Sponges lack true tissues, have no body symmetry, and are sessile; types are classified based on presence and composition of spicules.
Morphology of Sponges
Instead of true tissues or organs, sponges have specialized cells that are in charge of important bodily functions and processes.
Physiological Processes in Sponges
Sponges are sessile, feed by phagocytosis, and reproduce sexually and asexually; all major functions are regulated by water flow diffusion.