Which animal does not need gall bladder and why

Several species of mammals (including horses, deer, rats, and laminoids), several species of birds, lampreys and all invertebrates do not have a gallbladder,Horses don't have a gall bladder. In many other animal species including humans, dogs, cows, sheep, and goats.You can lead a perfectly normal life without a gallbladder. Your liver will still make enough bile to digest your food.

Molecules called lipids have long hydrocarbon chains that determine the way they act. they can be fats, oils, or hormones, and even exist in our cell membranes