AP BIOLOGY

Detailed explanation-1: -Sponges. Phylogenetically, the sponges (phylum Porifera) are the simplest of animals. They are multicellular and composed of specialized cells, arranged in a single layer, for the maintenance of life processes.

Detailed explanation-2: -Sponges are considered to be one of the simplest animals, primarily because their bodies are not organized in organ systems or even tissues. Rather, sponges are made up of a grouping of cells that work together to contribute to meeting the daily needs of the sponge.

Detailed explanation-3: -This phylum includes about 5000 species. Poriferans are pore-bearing first multicellular animals. The pores are known as Ostia. The poriferans have a spongy appearance and are therefore called sponges.

Detailed explanation-4: -The morphology of the simplest sponges takes the shape of a cylinder with a large central cavity, the spongocoel, occupying the inside of the cylinder. Water can enter into the spongocoel from numerous pores in the body wall. Water entering the spongocoel is extruded via a large common opening called the osculum.

Detailed explanation-5: -Protozoan’s have no organs for excretion. As they live in an aquatic habitat, their wastes are eliminated by diffusion through the plasma membrane.