EVERYDAY SCIENCE

Detailed explanation-1: -Flatworms are acoelomates that are characterized by having three germ layers (ectoderm, mesoderm, and endoderm) and lacking respiratory and circulatory systems. Acoelomates are invertebrates that do not have a coelom, or body cavity. With about 25, 000 known species, flatworms are the largest phylum of acoelomates.

Detailed explanation-2: -An acoelomate is an animal which lack a coelom, or formal body cavity. True body cavities form only in multicellular organisms with true tissues. Within this group, the eumetazoa, there are the organisms like coral and jellyfish, which have only 2 basic tissues.

Detailed explanation-3: -Among the acoelomate phyla, the members of Platyhelminthes (flatworms) have no body cavity, and the space between the gut and the body wall, when present, is filled with a spongy organ tissue of mesodermal cells through which tissue fluids may percolate.

Detailed explanation-4: -Porifera & Cnidaria are acoelomates. Examples of Porifera-Glass Sponges, Demospongiae, etc. Examples of Cnidaria-Corals, hydra, jellyfish, etc.