560 SCHEVILL, BACKUS, AND HERSEY [CHAP. 14 



A clear example of how sound may be used offensively is found in the snap- 

 ping shrimps of the genus Alpheus, which have been extensively observed in 

 aquaria by MacGinitie and MacGinitie (1949). The loud snap, earlier described, 

 is made when small fish or other organisms pass the burrow of the shrimp. 

 Animals of sufficiently small size are actually stunned by the concussive 

 sound and then are dragged into the burrow to be consumed. Presumably 

 animals so large as not to be stunned are repulsed by the act. 



C. Other Communicative Functions 



Sounds are used for manifold other purposes. For instance, Lindberg (1955) 

 has described apparently intimidative sounds of Panulirus interruptus when on 

 the verge of conflict. For similar purposes, jaw-snapping by dominant Tursiops 

 has been described by Wood (1954) and Tavolga and Essapian (1957). Other 

 examples are given by Backus (1958). Wood (1954) and others have cited cases 

 of mother and child porpoises calling to each other when separated. 



D. Orientation by Sound 



It has long seemed reasonable to suppose that marine animals use sound in 

 orientation, hearing being so much more useful, as we have said, than the other 

 senses. Nevertheless, beyond this general supposition and the realization that 

 communicative calls have orientational uses (flocking, station-keeping, etc.), 

 there is much speculation but little knowledge. That little knowledge is 

 almost all about a few individuals (mostly captives) of one species of porpoise, 

 Tursiops truncatus (McBride, 1956; Schevill and Lawrence, 1956; Kellogg, 

 1958), which evidently makes wide use of echo-location in food-finding and 

 obstacle-avoidance. Since the sounds so utilized are the varied series of clicks 

 described above (page 556) as common to all odontocetes the sounds of which 

 are known, it has seemed justifiable to assume that they all utilize these sounds 

 in echo-location. Much more needs to be learned, even for this one species. 



Although mysticete whales and many fish are soniferous, it is yet to be 

 shown that they use sound in this particular way, although there is no question 

 but that they might. Backus (1958, p. 196) has cited from various authors 

 instances in which cave fishes have maneuvered successfully without visual 

 clues, but, unfortunately, also without proof that they were in any way 

 soniferous. 



There has been much speculation on the possible orientationally acoustic 

 function of the lateral line system of fishes, which in its structure and disposition 

 suggests an array of listening organs. The latest thinking (T. J. Walker, un- 

 published, and J. Kuiper, unpublished) appears to be that instead of being 

 actually acoustic, it is rather a turbulence ("flow-noise") sensor, somewhat 

 analogous to Ogawa and Shida's suggestion (1950) of such a function for sinus 

 hairs on the faces of whales. 



