CONTRIBUTIONS FROM THE BIOLOGICAL LABORATORY OF THE BUREAl OF FISHERIES AT WOODS 



HOLE, MASSACHUSETTS. 



THl; FUNCTION OF THE LATERAL-LINE ORGANS IN FISHES. 



By G. H. PARKER, 

 Assistant Professor of Zoology, Harvard I niversity. 



INTRODUCTION. 



The habits of fishes, like those of most other animals, are inseparably connected 

 with their sense organs. Thus in the matter of feeding, Bateson (1890) has pointed 

 out thai probably the majority of tishes seek their food by sight. Many such fishes 

 when kept in confinement are known not to feed at night or even in twilight, though 

 they may be ravenous feeders in daylight. Other lishes. including the eels, skates. 

 sturgeons, suckers, flat-fishes, etc., many of which are bottom fishes and often noc- 

 turnal in their habits, seem not to depend upon sight in seeking their food. Their 

 powers of sight are often deficient, and food excites them chiefly through its action 

 on their organs of taste, smell, or touch. As Bateson observed, none of these lishes 

 start in quest of food w hen it is first put into their tanks, hut remain undisturbed for 

 an interval, doubtless until the scent has been diffused through the water. Then 

 they begin to swim vaguely about, and appear to seek the food by examining the 

 whole area pervaded by the scent. The search is always made in this tentative way, 

 whether the food is hidden or within sight, and it is first seized when by accident it 

 is come upon. 



Herrick (1903c) has made the interesting discovery that in the cat-fish, which 

 seeks its food in the way just described, the organs of taste pervade the whole skin. 

 and the fish will seize unseen food with great precision, provided only that it is brought 

 near the skin. Thus in this fish the organs of taste largely replace the eye as a means 

 of discovering the food. 



From these examples it must he clear how close is the relation between sense 

 organs and habits. The sense organs, in fact, are the usual means of initiating those 

 simple acts which, when taken collectively, constitute what are popularly known as 

 habits, for the sense organs are the avenues through which the external influences 

 enter the animal and excite it to action. How essential, then, in studying the habits 

 of any group of animals, must be a knowledge of their sense organs. 



From this standpoint the elucidation of the habits of fish is particularly 

 important, for their sense organs bear close comparison with those of human beings. 



