Epulopiscium  

What you should know:

Epulopiscium is among the largest known procaryotes at ~ 500 μm in length (seen here next to the smaller Paramecium). It is a Gram - positive rod that lives in the gut of the sturgeon fish.

Classification: 

Domain Bacteria

    Phylum Firmicutes

        Class "Clostridia"

Bergey's Manual Volume 3: The low G+C Gram-positive Bacteria

Links

• http://www.micro.cornell.edu/faculty/IMAGES/Epulopiscium.jpg
• K.D. Clements and S. Bullivant. An unusual symbiont from the gut of surgeonfish may be the largest known prokaryote. J. Bacteriol. 173(17):5359 - 5362, 1991.
• http://www.micro.cornell.edu/cals/micro/research/labs/angert-lab/images/epulo1.jpg