Question

Organisms without a body cavity are called The phylum representing the organisational grades named The outer layer is made of the tissue inside filling the body made and the lining of the gut is made of Organisms with a true body cavity completely lined wit THAN Their outer layer is also built from and their gut ning is made of They are represented by the phylur Organisms with a body cavity lined by both mesoderm As with the other grades, their outer layer is also built from and their gut ning is made of They are reeresented by the phylum Platyhelminthes seudocoelomates coelomates endoderm Nematoda coelomates Annelida

Answer 1

Organisms without a body cavity are called Acoelomates . The phylum representing this organizational grade is named Platyhelminthes. The outer layer is made of ectoderm, the the tissue inside filling the body is made of mesoderm, and the lining of gut is made of endoderm.

Organisms with a true body cavity completely lined with mesoderm are called Coelomates. Their outer layer is also built from ectoderm, and their gut lining is made of endoderm. They are represented by the phylum Annelida.

Organisms with a body cavity lined with both mesoderm and endoderm are called Psuedocoelomates. As with the other grades, their outer layer is also built from ectoderm and their gut lining is made of endoderm. They are represented by the phylum Nematoda.

Coelom is basically the body cavity which is lined with mesoderm between gut and the outer body wall.

Acoelomates do not posses the fluid filled body cavity instead the space between the digestive tract (gut) and the outer body wall is supposed to be hollow. So,instead of being hollow the empty space is filled with the mesoderm , the outer body wall is lined with ectoderm and the gut is lined with endoderm. The phylum that represents Acoelomates are Platyhelminthes, Porifera, Cnidaria, etc Also acoelomates have triploblastic body cavity that means their tissues and organs are developed from the three primary embryonic cell (germ) layers.

Coelomates also known as Eucoelomates possess true fluid filled body cavity within mesoderm called coelom. The outer body wall is lined with the ectoderm and the gut is lined with endoderm. The phylum representing this organizational grade include Annelida, Arthropods and Molluscs.

Pseudocoelomates have false coelom. Their fluid filled body cavity is not completely with mesoderm instead mesoderm is scattered and hence the body cavity of the psuedocoelomates is believed to be sandwiched between mesoderm and endoderm. Like the other organizational grades psuedocoelomates outer body wall is also lined with ectoderm and gut is lined with endoderm and the phylum representing psuedocoelomates include Nematoda, Nematomorpha, Rotifera, etc.