(ass-in-eat-a) , the arms of suctoria are mouths - so these are ciliates which have developed multiple mouths. The ends are expanded because many extrusomes used to catch the prey are located at the tips of the arms. this allows suctoria to be distinguished from heliozoa which do not have these expanded ends. Prey is caught after it bumbles into one of the arms, and then others may attach and begin to suck the cytoplasm out of the prey. One prey cell is caught to the right. Phase contrast.