Flatworms
			
Roundworms 
		
		
			
			
 
			
A flatworm has a thin, dorsoventrally flattened body. 
			
			

			Roundworms are more cylindrical in shape and tapered to a fine point at one end.
			
 
			
 
			

			 
		
		
			
			
 
			
Flatworms  are covered with cilia, hairlike growths. The gliding locomotion of a flatworm is powered by many tiny cilia on the outer surface of its body.
			
			
 Roundworms have a rigid outer covering called a cuticle that they shed repeatedly throughout their lives and as they grow.  Roundworms have longitudinal muscles that they contract to bend their bodies in a thrashing motion. 
			
 
			
 
		
		
			
			
 
			
Flatworms generally live in bodies of water.
			
			
 Roundworm species can live either on water or in soil.
		
		
			
			
 Flatworms are acoelomate, which means they do not have a body cavity. 
			
			
			
 
			
Roundworms are psuedocoelomate, which means they have a body cavity between their mesoderm and endoderm layers. 
			
		
		
			
			
 
			
The flatworm has a gastrovascular cavity, with only a single opening that functions as both mouth and anus. 
			
			
 The roundworm has a complete digestive tract, with two separate openings for the mouth and anus. 
		
		
			
			
 
			
Some flatworm species are also hermaphrodites, meaning they contain both male and female sex organs.
			
			
			
 
			
Roundworms have distinct males and females.