Animal oils and fats are water-insoluble, hydrophobic substances of animal origin. Animal oils consist predominantly of glyceryl esters of fatty acids, so-called triglycerides. The fatty acids composition of animal oils and fats varies and with that the physical properties.
In the land animal kingdom, the composition varies according to the animal species. In addition, it varies in a very complex fashion with the diet of the animal and the location of the fat within the animal. The composition also varies in relation to the health and well-being of the animal and the environment in which it matured.
Marine animal fats and oils are not only characteristically different in many ways from those of land animals, but they show differences depending on whether the fish was an oceanic or freshwater species and within a particular species whether it was caught in cold or warm water.