JONES: PROBABLE CAUSE OF CRATER WOUNDS 



Figure 8. — A hemispheroidal plug of unidentified fish 

 flesh from the stomach of an Isistiiis, central Pacific. 



found a very fresh plug of fish flesh complete 

 with integument and some scales (Figure 8). 

 The fishes from which these plugs were bitten 

 have not been identified. In order to find such 

 plugs, it is necessary to examine Isistins imme- 

 diately after capture because digestion will usu- 

 ally continue for a time after the specimen is 

 placed in formaldehyde or a freezer. 



DISCUSSION 



Further evidence relating Isistins to wounds 

 on fishes may be present in a photograph (Fig- 

 ure 9) of a crescentic wound on the caudal fin 

 of a swordfish (M. R. Bartlett, personal commu- 

 nication). The deep crescentic cut is opposed 

 by an arc of small dents and scars. The size 

 and arrangement of these correspond to the 

 small, hooked upper teeth of Isistius (Figure 6) . 

 In addition, a series of white scratches extending 

 from the small arc toward the crescentic cut ap- 

 pear to have been made by the upper teeth as 

 the shark backed away from the incomplete bite. 

 In this case, the shark's mandibular teeth must 

 have encountered the large, bony ray in the edge 

 of the caudal fin. The same fin bore an entire, 

 cut-out wound near the posterior border (Fig- 

 ure 10). 



The geographical distribution of records of 

 Isistius brasilie7isis (Strasburg, 1963; Parin, 

 1964) corresponds well with the general distri- 

 butions of the s]iecies of fishes which bear crater 

 wounds. Several authors (Mackintosh and 



Figure 9. — A crescentic wound on the caudal fin of a 

 swordfish caught in the Gulf of Mexico. Note the arc 

 of small dents opposite the cut, and the scratches pro- 

 duced by the shark's upper teeth as it backed away from 

 the incomplete wound. (Photo by Martin Bartlett.) 



Wheeler, 1929; Pike, 1951; Nemoto, 1955; van 

 Utrecht, 1959) have noted that fresh wounds 

 were seen only, or more frequently, on cetaceans 

 caught in the warmer waters of their migrations 

 and that those caught more poleward bore only 

 healed or partially healed scars. This was evi- 

 dence, they stated, that the animal producing 

 the wounds was an inhabitant of warm water. 



Some wounds on cetaceans described in the 

 literature were undoubtedly produced by lam- 

 preys (Pike, 1951). The majority of catch 

 records of lampreys in both the Pacific and At- 

 lantic, however, are near shore and in temperate 

 or cold waters which fits poorly the distribution 

 of fishes and whales bearing fresh crater 

 wounds. 



The largest crater wounds recorded (Mack- 

 intosh and Wheeler. 1929) were 4 or 5 cm by 

 7 cm. The smallest I have seen were 1.2 cm 

 by 2 cm. The smaller diameters of these cor- 

 respond well with the bite-widths I have esti- 

 mated for Isistiws at the extremes of the known 

 range of 14 to 50 cm, total lengths (Strasburg, 

 1963). 



All of the Isistius stomachs examined aboard 

 the Town-send Cromn'ell contained squid beaks 

 and pieces of squid pens. Strasburg (1963) also 



795 



