FISHERY BL'LLKTIN: VOL 69, NO- 3 



parasites are so small (1-3 mm long) in com- 

 parison with the size of other food items. For 

 example, 471 gnathiid isopod larvae were present 

 in one seiiorita gut, but being so small they con- 

 stituted only 35V' of the material. On the other 

 hand, a few algal fragments, with encrusting 

 bryozoans, made up AOV of the material in this 

 same specimen. However, only seven individ- 

 uals contained ectoparasites alone, as compared 

 with 17 that contained both parasites and free- 

 living prey. In all but one of these, the two 

 classes of material were sharjily divided in the 

 gut, usually with the free-living material poster- 

 iorly in a more advanced stage of digestion. Al- 

 though most of the ectoparasites in the gut had 

 undergone extensive damage and would not, by 

 themselves, have been identifiable to species, this 

 material usually graded gradually to freshly in- 

 gested specimens that were readily identified. 

 This fact, coupled with the circumstance that in- 

 dividual seiioritas tend to stay pretty much with 

 a single type of food organism during a given 

 period, greatly aided the task of analyzing this 

 material. 



Ectoparasites on the fishes. — To assess the sig- 

 nificance of cleaning in removing ectoparasites, 

 one must know what parasites occur on the fishes, 

 as well as the extent of the infestation. Thus 

 the survey of ectoparasites done in conjunction 

 with this work included essentially every fish 

 species exceeding 100 mm long regularly present 

 in the La Jolla study area, as well as every spe- 

 cies that was seen being cleaned there. Ecto- 

 ])arasites infesting these fishes include 33 spe- 

 cies of copepods, one species of brachiuran, two 

 species of isopods, one species of leech, and one 

 species of monogenetic trematode. Following is 

 a brief summary of the information being com- 

 piled on these parasites in collaboration with R. 

 F. Cressey. 



Copepods are the predominant ectoparasites 

 on fishes in this area. The 33 species represent 

 seven families: Bomolochidae (6 species), 

 Caligidae (13 species), Dichelesthiidae (2 spe- 

 cies) , Lernaeidae (1 species), Chondracanthidae 

 (5 species) , and Lerneopodidae (6 species) . The 

 one species of the closely related brachiurans is 

 a member of the family Argulidae. The bomolo- 



chids, which were found on 12 species of the 

 fishes sampled, are mobile forms about 2 mm 

 long (all lengths of parasites here and below do 

 not include egg cases) that occurred mostly on 

 the gills of their hosts. The caligids, which in- 

 fested 29 species of the fishes, are mobile forms, 

 2 to 4 mm long, that occurred mostly on the ex- 

 ternal body surface of their hosts, although two 

 species were found only in the oral cavity. The 

 dichelesthiids are highly modified forms about 

 2 mm long that were attached to the gills of two 

 species. The lernaeid is a highly modified form 

 about 5 mm long that was attached to the fins 

 of 12 species. The chondracanthids, which in- 

 fested five species, are highly modified forms, 3 or 

 4 mm long, that lived attached in the branchial 

 chamber, including the gills, of their hosts. The 

 lerneopodids, infesting eight of the fish species, 

 are highly modified forms, 2 to 5 mm long, mostly 

 living attached in the branchial and oral cavities, 

 although one individual fish carried several at- 

 tached to its dorsal fin. Finally, the argulid 

 is a mobile form about 2 mm long that was found 

 on the outer body surface of one species of fish. 

 The fish species hosting representatives of the 

 different copepod and brachiuran families are 

 listed in Table 2, and examples of the six copepod 

 families are illustrated in Figure 7. 



Thus a variety of ectoparasitic copepods occur 

 on the fishes, but only caligids were found among 

 the gut contents of the cleaners. Further- 

 more, although 13 species of caligids (five spe- 

 cies of the genus Caligus and eight species of 

 the genus Lepeoiihtheirus) occur on fishes in this 

 area, only a relatively few of these are significant 

 as prey of the cleaners, as noted below. 



Of the two isopods, one, Livoneca vulgaris, a 

 large parasite, about 20 mm long, was found in 

 the branchial chamber of just one species of fish 

 and was not found to be jirey of the cleaners. 

 On the other hand, the highly mobile gnathiid 

 larvae (Figure 8), which are about 2 mm long, 

 are a major prey of the cleaners. Only one form 

 of gnathiid was readily recognized, but more 

 than one species may occur among this material. 

 Parasites of the body surface of fishes, the gnath- 

 iid larvae were taken on 11 of the fish species 

 sampled, l)ut I suspect that they are actually 

 more widespread and abundant than these data 



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