NEET BIOLOGY

Detailed explanation-1: -The sponges (phylum Porifera) are among the simplest of the invertebrates. Sponges can be described as organized masses of specialized cells that carry out bodily functions. Most sponges are ocean dwellers, but a few are found in fresh water. Approximately 5, 000 species have been described.

Detailed explanation-2: -The simplest body structure in sponges is a tube or vase shape known as “asconoid", but this severely limits the size of the animal. The body structure is characterized by a stalk-like spongocoel surrounded by a single layer of choanocytes.

Detailed explanation-3: -The simplest of all the invertebrates are the Parazoans, which include only the phylum Porifera: the sponges.

Detailed explanation-4: -The most basic body plan is called asconoid. In asconoid sponges the two major cell layers surround a fluid-filled cavity called the spongocoel, the large central cavity of sponges .

Detailed explanation-5: -The simplest animals include the sponges (Porifera) and the Cnidaria. Sponges are unsymmetrical or radially symmetrical, with many cell types but no distinct tissues; their bodies contain numerous pores and sharp protective spicules.