PARASITIC HELMINTHS 



By Asa C. Chandler, Rice Institute, and Harold W. Manter, University of Nebraska 



The helminth parasites of the Gulf of Mexico, 

 with the exception of the trematodes, have been 

 studied very little. The bulk of the collecting 

 done so far has been at the former Biological 

 Laboratory of the Carnegie Institution at Dry 

 Tortugas, Florida, at the eastern side of the Gulf. 

 A few desultory investigations or reports of one 

 or a few species have been made at other points 

 on the United States coast and from the north 

 coast of Cuba, but with the exception of one new 

 species of trematode reported from a manatee no 

 studies have yet been made along the extensive 

 Mexican coast where many new helminths will 

 probably be found, particularly in the non- 

 migratory fishes of the shallower waters and 

 bays. Practically all the work done so far has 

 been taxonomic and morphological, dealing either 

 with adult or larval forms. Of more than 200 

 species of trematodes from Gulf animals only 3 

 life cycles have been studied, and the life cycles of 

 none of the cestodes, acanthocephalaas, or nem- 

 atodes have been studied at all. 



The only parasitic helminths of Gulf animals 

 that have thus far been studied comprehensively 

 are the trematodes of oceanic fishes and these only 

 at Dry Tortugas where the pioneer work was done 

 by Linton (1907-10) followed by an extensive 

 study by Manter from 1930-49. Linton also did 

 some pioneer work on the other parasitic helminths 

 of Dry Tortugas, but this work has not been fol- 

 lowed up as has the work on the trematodes. It 

 was observed by Linton, however, that Acantho- 

 cephala and Nematoda, both in adult and larval 

 stages, are relatively scanty in fishes of Dry 

 Tortugas and in fishes of other southern regions 

 (Bermuda and North Carolina) as compared with 

 their occurrence in fishes at Woods Hole, Mas- 

 sachusetts. Larval cestodes, also, were relatively 

 scanty except adult Tetraphyllidea and Try- 

 panorhyncha in selachians which compared favor- 

 ably with the numbers found in the Woods Hole, 

 Massachusetts, area. 



Chandler (1935a), in a study of 23 species of 

 fish from various parts of Galveston Bay, pointed 

 out a great excess of immature over adult stages 

 of parasites, 15 of 25 of the species identified 

 being larval or immature stages; a scarcity of 

 flukes and adult tapeworms (no elasmobranchs 

 were included in the study) ; a predominance of 

 Acanthocephala as common adult parasites; and 

 very marked differences in the helminth fauna in 

 local areas, even in the very limited region in- 

 cluded in the study. These differences are prob- 

 ably associated with the local distribution of 

 definitive hosts in the case of immature species 

 and of intermediate hosts in the case of adult 

 species. Of 10 species of adults and 15 of im- 

 mature species, 9 of the former and 1 1 of the latter 

 were previously undescribed species. This is in 

 contrast to the findings of Manter in oceanic 

 species of fish from Dry Tortugas and suggests, 

 as remarked above, that many new species of 

 fish helminths will be found when the parasites 

 of nonmigratory species of the shores and bays of 

 the western and southern sides of the Gulf are 

 studied. 



In preliminary studies on marine fishes from 

 Corpus Christi Bay, Tex., Aaron Seamster (1950) 

 reported in a personal communication that of 30 

 fish examined, belonging to 16 species, parasites 

 were found in 27. The heaviest load was in the 

 yellow-tail, Bairdiella chrysura. However, only 

 1 specimen, Menticirrhus americanus, was infested 

 with an acanthocephalan, Illiosentis furcatiis, and 

 only 1 specimen, Synodusfoetens, with a nematode. 

 A few cestode infections were reported. 



In addition to the trematodes, cestodes, acantho- 

 cephalans, and nematodes considered in the fol- 

 lowing sections a few other parasitic or semi- 

 parasitic helminths have been reported from the 

 Gulf. Several polyclad turbellarians are as- 

 sociated with particular marine organisms on 

 which they are predatory in a semi-parasitic 

 fashion. Stylochus frontalis is common in Gulf 



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