A review of the supposed phylogenetic development of adipose tissue in invertebrates and vertebrates is presented. In invertebrates, lipid-storage tissue is absent in the sponges and coelentera tes. There is some evidence of such tissue in Echinoderms, a speculated possibility in Annelids, Mollusks, Crustaceans and Arachnids, and well-developed tissue in Myriapods and insects; but no distinct adipose tissue in Cephalochords. In vertebrates, the poikilotherms have only traces of adipose tissue, the liver performing a lipid-storing function. Fishes, amphibians, and reptiles have little or no highly developed white adipose tissue. Carnivores have very little white adipose tissue, while hibernating mammals have large amounts of lower-developed brown adipose tissue. These observations do not correlate with the prediction of the mega-evolution model of a graded increase in quantity and quality of tissues with advancement up the so- called evolutionary ladder of life.