ABSTRACT

The classically presented asteroid digestive system is that of the family Asteriidae. Although a few authors described rather different digestive structures which characterize other families, Anderson was the first to clearly show that the asteroid digestive system shows fundamental variations according to the family. The gross asteroid digestive anatomy may be summarized as follows: the mouth opens in the mid-ventral part of the body and is surrounded by a peristomial membrane attached to the peribuccal skeleton. The digestive system of asteroids is frequently voluminous. In most species the coelom of the disc is almost fully occupied by the central digestive organs, and the coelom of the arms by the pyloric caeca. The digestive organization of Porcellanasteridae resembles that of Luidiidae in the absence of the intestine, rectal caeca, rectum and anus. Digestive organization of these globular asteroids is highly specialized and is rather different than those of most other asteroid families.