Mar., 1905.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



59 



The Ears of Fishes. 



By W'li.i RED Mark Webh, F.L.S., Honorary Secre- 

 tary of the Selborne Society. 



With Illustrations from Photographs by the Writer. 



Those who look only at the outside of a fish's head 

 may, perhaps, be pardoned for jumping to the con- 

 clusion that it has no ears because there are no external 

 evidences of their presence. At the same time we have 

 only to recall the accounts which exist of carp rcgu- 



■ig. I.— The Right 

 semi-circular ca 

 5een from the oute 



[.iiifliloiii i„i,^,ili-) of a Cod, showing the 

 large otolith or sagitta in position, 

 slightly enlarged. 



larly coming to be fed at the sound of a bell to appre- 

 ciate that fishes hear, and, therefore, must have 

 auditory organs of some kind. Dr. Zenneck, of Strass- 

 burg, has also shown by special experiments that fishes 

 are sensitive to sound vibrations and are frightened 

 when an electric bell is rung under water. Care was 

 taken by first placing the bell in a pail to prevent any 

 disturbance of the water which might alarm the fish. 

 As a matter of fact, the ears of these animals are well 

 developed, and differ only in matters of detail from our 

 own; though in these very points of difference much 

 of their interest lies. If we look at the first illustration, 

 which is the photograph of the internal ear of the cod- 

 fish (I'ig. i), we shall see that the three semi-circular 



Fig. 2.— The Large Otoliths of the Cod. 



canals arc present which we find in the higher verte- 

 brates, and which it is generally supposed enable us to 

 judge of the position of our heads with regard to our 

 bodies and to the earth's surface. 



We notice, however, that the spiral prolongation of the 

 sacculus, which we know as the cochlea, is absent frt)m 

 the fish, and we do not see the three small bones which 

 play an important part in connection with vibration in 

 the mammalia. There is a very good reason for this, 

 for in fishes these bones are still put to their original 

 use and form part of the ordinary skull. In bony fish, 

 however, we find otoliths, or stony structures (Fig. 2), 

 which may be of a large size and situated in special 

 parts of the internal ear. Many of these ear stones 

 are of peculiar shapes, and though the majority are 

 white in colour, they are usually finely sculptured in a 

 characteristic manner. There is no doubt that they 

 make an attractive collection, and are surrounded with 

 a good deal of interest, as we shall see. 



We may first of all ooint out that there are typically 

 three otoliths, and their positions are shown on the ac- 

 companying diagram (Fig. 3) taken from a drawing 

 made bv Mr. E. T. Newton, of Jerm)^ Street Museum, 



-circu/ar ra/eal 



Sfmi - cum/ar 



i-'ar/ul 



Fi/rifcrm 



LAPILLUS 



-The Left Auditory Capsule of the Pike 

 side, showing the positions of the vari 



(Modified frum a drimimj h,j E. T. Nar 



M/'^c ijti/?if/ta/' 



seen from the inner 

 'US otoliths, 



in, F.R.>>.) 



which he has been so kind as to put into my hands. The 

 largest otolith is the "sagitta," which lies in the 

 sacculus and is seen also in the first illustration. The 

 second is situated not far from the first in that part of 

 the ear which corresponds to the cochlea. The third 

 is in one part of the utriculus, and is called the lapillus. 

 The sagitta is usually the largest, and, therefore, is the 

 easiest to find, especially in fish that have been cooked 

 and brought to the table; for it is possible to pursue 

 the study of otoliths, on occasion, at meal times. Some 

 amusement can be had by those familiar with these ob- 

 jects at restaurants should small haddocks be served 

 up under the name of whiting. The flavour may lead 

 the diner to doubt the claims of the fish to its title, but 

 few external characters, if any, remain which would 

 piove it to be an impostor. Whitings and pseudo- 

 whitings perforce are cooked with the head in place, 

 and very little trouble will serve to make 

 matters quite clear. The large otoliths can easily I:e 

 removed with one's knife and fork from the back of the 

 skull and the species of fish determined without a doubt. 

 The sagitta in the haddock (Fig. 4) resembles that of 

 the cod (Fig. 2), though it is longer and somewhat 

 narrower in proportion, while that of the whiting 

 (Fig. 5) is produced into a long point and is larger com- 

 pared with the size of its owner. With this evidence 

 up one's sleeve, should one be acquainted with the 



