A siloma is a body cavity that originates from the mesoderm and covers the mesodermal cell layer called the peritoneum. Animals can be classified into the following groups on the basis of the variety of silom. 1. Acoelomate : In their body, during embryonic development, instead of siloma, the inner space (blastocyst) is filled with mesodermal spongy parenchyma cells. Porifera, Cnidaria, Ctenophora, Platyhelminthes etc. Examples- Hydra viridis ( Hydra) , Fasciola hepatica ( liver worms) etc. 2. Pseudocoelomate or pseudocoelomate : These animals also have no silo, but sometimes place the mesodermal cell layer around the inner space (blastasil) during embryonic development . But the cells never completely encircle the blastocyst, creating a full cell layer or peritoneum. Nematoda, Rotifera kinorhyncha, etc. Example- Loa loa ( eye worm). 3. Eucoelomate or eucoelomate : Eucolomate is an eucoelomatous animal because the eelomete originates as a cavity from the inside of the embryonic mesoderm and is completely enclosed in the peritoneum layer composed of compressed , mesodermal epithelial cells. Eucalyptus is considered to be a relatively advanced animal. Eucalyptus belongs to the genus Mollusca, Annelida, Arthropoda, Echinodermata, Hemichordata, Chordata etc. Examples- Metaphire posthuma ( earthworm) , Culex pipies ( mosquito) , Asterias vulgaris ( sea star) , Tenualosa ilisha (ilish ) etc.