Anatomy

Ampulla- contracts to let water enter the tube foot
Anus- mouth of the digestive tract allowing waste eject
Body wall- produce secretions and excretions
Esophagus- it allows food to reach the stomach. 
Gonad- producing gametes 
Intestine- section of the digestive tract between the stomach and the anus 
Madreporite- is an opening used to filter water into the water vascular system
Mouth- anterior cavity of the digestive tract 
Pyloric caeca- producing digestive enzymes 
Pyloric duct- it receives water from the annular canal 
Pyloric stomach- it receives food to be digested.
Rectal caeca- where waste is stored before being expelled through the anus
Ring canal- circular canal in which filtered water enters