GENERAL HISTOLOGY

Detailed explanation-1: -Sponges are multicellular animals, unique in many ways. They are the only group of animals that can be classified as asymmetric, which means they possess no symmetry at all. There is no plane through their bodies where you could cut them in half to produce two mirror images.

Detailed explanation-2: -Sponges are unsymmetrical or radially symmetrical, with many cell types but no distinct tissues; their bodies contain numerous pores and sharp protective spicules. Coelenterates (phylum Cnidaria) are radially symmetrical, with two tissue layers (ectoderm and endoderm) surrounding an all-purpose gastrovascular cavity.

Detailed explanation-3: -Note: Scypha belongs to phylum Porifera. These organisms are sessile, that is they remain attached to the substratum. The internal skeleton is made up of calcareous spicules and the water vascular system is well developed. Scypha demonstrates radial body symmetry.

Detailed explanation-4: -Only Demospongiae are asymmetrical whereas the other two classes have symmetrical body structure. Demospongia is the most abundant living sponges containing 90% of known species of sponges.

Detailed explanation-5: -Sponges have no body plan and are asymmetrical.