and decaying marine vegetation. Morphology Trimastix cells are oblong broad anteriorly and taper posteriorly. Trimastix is 20 µm long and 8 µm wide. A kinetid of four flagella is located on the anterior end of the cell with one flagella anteriorly oriented, two flagella posteriorly oriented, and the fourth flagella sitting within an oral groove on the ventral side. Trimastix species do not have mitochondria, but they do have remnants of an ancestral mitochondria, in the form of a mitosome. There is no evidence this mitochondria-like organelle produces ATP, but there is evidence that the glycolytic pathway is intact within it. The mitosome also still appears to be targeted by proteins involved in amino acid metabolism, transport and maturation of proteins and transport of metabolites so it likely retains some mitochondrial function relating to those areas. Trimastix have one anterior pear-shaped nucleus that contains a large nucleolus, with the exception of Trimastix marina which has two nuclei. References Metamonads Excavata genera