The ethyl esters are absorbed, particularly if you take them with a fatty meal that will stimulate your digestive juices. The probably the best absorbing forms are the triglyceride. There's also a form called a free fatty acid, which is not hooked to anything.
Bill Harris, PhD is an internationally recognized expert on omega-3 fatty acids and fish oil. He has more than 300 publications relating to fatty acids, including omega-3s, in the medical literature.