CHAPTER III 



SURVEY OF INVERTEBRATES FOR ANAEROBIOSIS 

 I. PROTOZOA 



1. NON-PARASITIC PROTOZOA 



A. Occurrence in anaerobic habitats. In most cases 

 in which it is claimed that non-parasitic protozoa can 

 live anaerobically, this conclusion was reached after the 

 animals had been found in surroundings that appeared 

 oxygen-free with the currently accepted methods for 

 oxygen analysis. In some instances more refined methods 

 failed to show molecular oxygen. However, even if traces 

 of oxygen have been overlooked, there is hardly a doubt 

 that in most cases the quantity was too small to exert any 

 significant influence on the direction of the metabolism. 

 This applies especially to the organisms mentioned be- 

 low that are injured by oxygen. So the claim that pro- 

 tozoa occurring in apparently anoxic habitats may be 

 true anaerobes seems justified. 



One of the most important anaerobic protozoan faunas 

 is represented by the sapropelic protozoa {cf. Appendix, 

 Table 1), among which the most characteristic types are 

 ciliates (Lauterborn, 1908, 1916; Noland, 1927; Wetzel, 

 1928). However only those ciliates should be regarded 

 as truly anaerobic, i.e., dependent on anaerobic metabol- 

 ism or capable of a permanently anaerobic life, which 

 live actually within the mud or in the thin water layer 

 in immediate contact with it. Here Wetzel (1928) found 

 the following forms : various species of Metopus, Caeno- 

 morpha, Plagiopyla, Epalxis, Discomorpha and Sapro- 

 dinium, Lagynus clegans, Dactylochlamys hystrix, 

 Chaenia binuclcata, Pelomyxa biitschlii and Ludio par- 

 vulus. He considers, in addition, as regular members of 

 the anaerobic layer the following ciliates observed by 

 Lauterborn (1916) : Chaenia limicola, Legendrea loyesae, 



