Which animal is known to lack a gall bladder?

The horse is known to lack a gall bladder, making it the correct answer. In horses, bile is produced continuously by the liver and is secreted directly into the intestine, which is an adaptation to their natural diet of high-fiber materials. This continuous secretion is necessary for the efficient digestion of fibrous plant materials, as horses graze throughout the day rather than consuming large meals at once, which is often the case with animals that have gall bladders, such as cows, cats, and birds. Without a gall bladder, horses can more effectively manage their digestive processes according to their grazing habits.