Phylum Porifera: Phylum Porifera includes pore-bearing animals. These are commonly called sponges. They are the oldest and most primitive metazoans. Porifers evolved in the Proterozoic era more than 600 million years back. Porifers were known to Aristotle, the father of zoology. John Ellis (1765) established the animal nature of sponges. The term Porifera was coined by Robert Grant (1836). Characteristics of Phylum Porifera: They are radially symmetrical, multicellular, diploblastic with the cellular level of organization. They are mainly marine except few (Spongilla), sedentary and colonial or solitary with significant water transport mechanism. The body wall consists of two imperfect cellular … Continue reading Phylum Porifera