GENERAL HISTOLOGY

Detailed explanation-1: -Members of the phylum lack tissues or organs and consist of only two layers of cells. They are filter feeders and are distinguished by having so called collar cells that are ciliated and responsible for food uptake.

Detailed explanation-2: -They are multicellular but do not have tissues or organs. The name porifera means ‘pore bearer’ in Latin. The surface of the sponge’s body is covered by a skin, one cell thick.

Detailed explanation-3: -Unlike Protozoans, the Poriferans are multicellular. However, unlike higher metazoans, the cells that make up a sponge are not organized into tissues. Therefore, sponges lack true tissues and organs; in addition, they have no body symmetry. Sponges do, however, have specialized cells that perform specific functions.

Detailed explanation-4: -This is because sponges evolved much earlier than other animals. In fact, sponges do not even have true tissues. Instead, their bodies are made up of specialized cells (cell-level organization) that do specific jobs.

Detailed explanation-5: -Sponge belongs to phylum Porifera. It has cellular level of organization and thus, there are no definite organs or organ systems. They have a porous body through which water flows.