ABSTRACT
The digestive systems of echinoids consists of the digestive tract, cœcae, siphons, siphonal grooves and sphincters, and the digestive tract forms the mouth, buccal cavity, pharynx, esophagus, stomach, intestine, rectum, periproctal cavity and anus. Earlier separations of the digestive tract are based on the morphology and histology of the digestive tract of endocyclic echinoids.
