A coelom is a cavity that separates the gut from the body wall. Most animals are coelomates, meaning they have a coelom. The coelom allows the body's internal organs to develop independently of the body wall.nimals without it, such as flatworms, are called acoelomates. In between there are some animals called pseudocoelomates, which possess a false coelom, which is an unlined or partially lined body cavity between the gut and body wall. A coelom is defined as a cavity that separates the gut from the body wall.