Digestion of fats is also similar in both invertebrates and vertebrates. Lipases are the - enzymes that hydrolyse fats. A single lipase can catalyse many steps in the breakdown of fat. The vertebrate pancreas secrete an enzyme lipase but before it breaks down fat, some detergent-like action is needed to emulsify the fat droplets. Bile salts from the liver, lecithin and cholesterol form miscelles and do this job. They reduce the surface tension at the fat-water inter phase in a slightly alkaline medium and tiny emulsification droplets of fat are formed. Then the lipase begins to digest the emulsified droplets.
The resultant fatty acids and monoglycerates are kept in solution by help of bile salts again and are finally absorbed. Glycerol is water soluble and easily absorbed and metabolised. Fat like butter is absorbed directly through the intestinal epithelium without hydrolysis.