PROTOZOA 



By Victor Sprague, Lake Chatugue Biological Laboratory 



The Protozoa considered here inchide all the 

 orders recognized by Pearse (1949) excepting 

 Dinoflagellata and Forminifera,^ these two groups 

 being so abundantly represented in the Gulf of 

 Mexico and relatively so well-known that they 

 are given separate treatment. Nothing which is 

 said below, therefore, is to be construed as apply- 

 ing to those orders excepting when they are spe- 

 cifically mentioned. An attempt has been made 

 to list in this paper every protozoan which has 

 been reported from the Gulf. Although it is 

 believed that most of the important papers have 

 been reviewed, it is quite possible that some of 

 them have been overlooked. 



The number of species in any particular order 

 which have been recorded in the literature per- 

 taining to the Gulf does not by any means give an 

 indication of the extent to which that order is 

 actually represented there, since relatively only a 

 very few studies on Protozoa of the Gulf of Mexico 

 have been conducted. When each order is con- 

 sidered below, therefore, not only are the reported 

 species (if any) listed but a statement is usually 

 made to indicate whether or not an investigator 

 would expect to find numerous representatives of 

 that group living under the conditions existing in 

 the Gulf. For instance, one would not expect to 

 find in the marine habitats many representatives 

 of Euglenoidina or Heliozoa, which are predomi- 

 nantly fresh water forms, or members of Hyper- 

 mastigina, which are exclusively inhabitants of 

 the alimentary canal of certain land dwelling 

 insects. On the other hand, such orders as 

 Radiolaria, which are exclusively marine, and 

 Microsporidia, which are common parasites of 

 invertebrates and lower vertebrates living in 

 almost any conceivable habitat, are probably very 



' The writer is indebted to Paul S. Oaltsort and Harold W. Harry for 

 invaluable aid in obtaining pertinent literature and to Sewell H. Hopkins 

 for criticism of one portion of the manuscript. 



> See articles by H. W. Oraham, Dinoflagellates of the Gulf of Mexico, 

 pp. 223-226 of this book, and by F. B. Phleger and F. L. Parker. Gulf of 

 Mexico Foraminifera, pp. 235-241. 



259534 O— 54- 



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abundantly represented both in variety of species 

 and numbers of individuals. 



To anyone interested in Protozoa of the Gulf 

 of Mexico there is a striking contrast between the 

 apparently limitless variety of species there and 

 the very scant attention which protozoologists 

 have given them. The semitropical climate and 

 the great diversity of habitats found in the Gulf 

 proper and its contiguous waters undoubtedly 

 provide suitable environments wherein a corre- 

 sponding diversity of species of free-living pro- 

 tozoan fauna not only are able to live but can 

 reproduce rapidly and flourish. The same favor- 

 able conditions give rise, also, to a great abundance 

 and variety of other invertebrates and fishes which 

 serve as hosts of protozoan parasites. Numerous 

 species of the parasitic Protozoa not only find 

 suitable hosts, but the relatively high temperatures 

 of the southern waters are accompanied by rapid 

 multiplication of these parasites and, consequently, 

 theu- occurrence in great abimdance. Although 

 several of the species of Protozoa reported to occur 

 in the Gulf were previously known ones, the over- 

 whelming majority have been new. This fact 

 alone suggests that any serious investigator would 

 be riclily rewarded for his efforts by many dis- 

 coveries. The Protozoa of the Gulf of Mexico, 

 both free-living and parasitic, constitute one of 

 the great American frontiers in protozoology. A 

 few individuals have probed its fringes, but its 

 thorough exploration is a task for future investi- 

 gators to undertake. 



SURVEY OF THE LITERATURE 



The known Protozoa of the Gulf of Mexico 

 (exclusive of Dinoflagellata and Foraminifera) are 

 mostly free-living amoebae, ciliates (both free- 

 living and parasitic), and Sporozoa. The first two 

 groups have been studied chiefly along the Florida 

 coast and the third along the coasts of Texas, 

 Louisiana, and Mississippi, especially at Louisiana 

 State University Marine Laboratory loc^ited on 



243 



