Table 9.- — Sites of occurrence of Colobomatus goodingi in the cephalic lateral tine canals of 

 Strongylura notata from the Bahama Islands 



infested, and all 14 specimens over 108 mm. BL 

 were infested in 1963. Two specimens (76-80 mm. 

 BL) from Crooked Island and five (58-65 mm. 

 BL) from Bimini were uninfested in the 1963 col- 

 lection. The average number of CoJohoiruittis sites 

 per fish (over 80 mm. BL) was 1.0 in 1927, 1.5 in 

 1935, and 2.6 in 1963. Thus, in this small sample, 

 relative infestation seemed to be increasing over 

 this time span. 



Information is more plentiful on geographic 

 variation in infestation. For example, the inci- 

 dence of infestation by Paraboniolochus beUones 

 generally decreases from the Atlantic to the west- 

 ern Pacific (tables 4 and 5), probably because of 

 competition with P. sinensis and the two species 

 of N otlioh(ymolochus. 



The infestation of Platyhclone nrgahis with 

 juvenile stages of (htligus sp. varies widely from 

 area to area. In the eastern Atlantic 42 percent of 

 the P. argalus were so infested (table 4) ; this 

 figure reaches nearly 100 percent if tlie uninfested 

 populations at some island groups (Azores, Cape 

 Verdes, Ascension, and St. Helena) aj-e eliminated. 

 Of 46 P. a. armobonensis taken at Annobon Island 

 in 1964 and 1965, all but 3 had juvenile Caligus 

 attached to the fins, and as many as 13 copepods 

 were picked off a single needlefish. However, none 

 of 1 1 P. a. annohonensis taken at the nearby island 

 of Fernando Poo had any copepods. 



Another clear example of geographic differences 

 in infestation was found in Tylosui'us acus. All 

 populations were infested with f'aligodes, L. 

 fylosuri, and Colobomatus except for the Mediter- 

 ranean T. acus imperialis, on which no copepods 

 were found. This gross difference in infestation of 

 the Mediterranean population of 7\ acus from the 

 western Atlantic T. a. acus and the Gulf of Guinea 

 T. a. rafale lends support to the taxonomic distinct- 

 ness of the Mediterranean population. 



Rather large amounts of interarea variation ap- 

 pear in the infestation of Ablerines hians, Ty- 

 losurus acii^s, and 7'. crocodilus by Caligodes 

 laciniatus, LeiTianthropu-s fylomiri, and Colobo- 

 inatus goodingi. Some of this variation is no doubt 

 due to differences in sizes of the hosts, larger hosts 

 being more likely to be infested ; some is defuiitely 

 correlated with geography. For example, Colobo- 

 matus was found on only two large western 

 Atlantic Ablennes and on no Indian Ocean speci- 

 mens, yet it was very common in the Gulf of 

 Guinea (41 percent). Interestingly, a similarly 

 low rate of infestation by Lemanthropus tylosnt^i 

 was found in the western Atlantic and the Indian 

 Oceans. 



At present, we can offer no explanation for these 

 differences in infestation. The geogi-aphic differ- 

 ences are important in indicating restricted amount 

 of interchange between populations of needlefishes 

 and so serve to point out those populations that 

 may be taxonomically distinct. 



Nature of the Symbiotic Relationship 



It is difficult to assess accurately the true nature 

 of the relationship that exists between most species 

 of "parasitic" coi:»epods and their hosts. In the ab- 

 sence of measurable or observable damage to host 

 tissue, it is open to question whether or not an or- 

 ganism is parasitic in the strict sense or if the 

 relationship is commensalistic or mutualistic. For 

 purposes of this discussion parasitism is defined as 

 a relationship in which the host suffers tissue dam- 

 age or is impeded in efficiency because of the pres- 

 ence of "parasites." Commensalism is that relation- 

 ship whereby the host provides slielter (]ii-otection) 

 or food to the "conimciisar' and neither suft'ei"s 

 hardship nor benefits. Mutualism is defined as that 

 relationship whereby both organisms benefit. I^n- 

 less exhaustive life history observations are made. 



COPEPODS AND NEEDLEFISHES 



429 



