FISHES 139 



Though quietness is the first essential of the " gentle 

 art," it is still a matter for debate as to how far fish can be 

 actually said to hear. The ordinary organs of hearing are 

 entirely absent, but experiments have proved that many 

 fish are highly sensitive to vibrations, whether above or 

 below water, and since sound or vibrations travel faster 

 below than above water fish readily detect the slightest 

 disturbance of their element. 



What corresponds to the normal ear in fishes consists 

 of a membraneous sac enclosed in a bony chamber on 

 either side of the back of the head, and each sac contains 

 three canals or chambers containing limey concretions 

 which are imminently sensitive to vibrations and which 

 further aid in maintaining the balance of the fish. The 

 largest of these structures is known as the otolith, and in 

 some fishes, such as the Ling and Bream, attain consider- 

 able proportions. An interesting feature common to all 

 otoliths is that they bear numerous concentric rings, each 

 marking the cessation of annual growth, which occurs 

 usually in winter when the fish feeds less. Comparatively 

 recent research has shown these rings correspond to other 

 rings borne upon the scales, the two between them con- 

 stituting, up to a point, reliable records of the fish's age. 

 When far advanced in years, however, these annular rings 

 are liable to become obliterated and therefore the potential 

 longevity of any given species is largely conjectural. 

 More is known regarding the age of fresh- water fishes than 

 those that inhabit the seas. Domestic Carp are believed 

 to be very long-lived, but according to Dr. Tate Regan, 

 who has made a study of the age of fishes, in the wild state 

 the fish probably does not exceed 15 years. Fish age 



