(pear-o-knee-ma) is one of the better known gliding heterotrophic euglenids. The body is referred to as sac-shaped but this applies best to P. trichophorum, the most common species and the one illustrated here. At first glance, it would seem that there is just one flagellum, but careful observations reveal a second flagellum tightly adpressed to the body or lying in a groove in the body surface. At magnifications such as this, this species usually cannot be distinguished from Jenningsia
, which has a single flagellum. The recurrent structure looks a little wider than the normal ridges of the body. The body is metabolic - meaning it squirms, and members of this genus have an ingestion organelle with which to manipulate food into the body. Animations by Rosemary Arbur of flagellar beat patterns are available here
.Differential interference contrast.