PISCES 259 



is dependent on the taste buds. Fish are extremely sensitive to 

 variations in acidity and alkalinity in the water. 



Vision. — Fish are able to change color, adapting themselves to 

 the background. When blinded, they are unable to thus adapt 

 themselves. Experiments of Lyon showed that fish see the banks of 

 streams, and will react to currents of water even if not directly in 

 contact with them. 



Tactile and Kinesthetic Senses. — Currents and surface waves are 

 apprehended by fish through the general cutaneous nerves for touch. 

 In general, fish react to stream pressure, aligning their bodies to 

 face the current. 



Lateral Line. — Parker holds that the lateral line nerves serve in 

 an auxiliary capacity aiding the general cutaneous nerves in rheo- 

 tropic responses. Lateral line organs are stimulated by vibrations 

 of low frequency, about six per second. Parker concludes that 

 lateral line organs are intermediate in function between the organs 

 of touch and the ear^ the latter being sensitive to vibrations of high 

 frequency. 



Hearing. — The surface between the air and the water is a screen 

 through which little sound passes. Vibrations of the water induced 

 by foot-falls on the bank are not to be confused with stimuli affecting 

 the sacculus, which Parker believes to be the chief organ of hearing. 

 During the recent war Parker, experimenting with cannon fired 

 near the surface of the water, found that fish were driven away 

 by the concussion. As vibrations of the air were transmitted to 

 the water it is difficult to believe that true hearing was evidenced. 



Messmates and Associates. — The small horse mackerels 

 ( Carangidae) swim in the shelter of large jelly fishes. A small fish 

 {Amphiprion) lives inside the large sea anemone {Crambactis) . 

 Fierasfery a small fish, lives in the hind-gut of the sea cucumber. 

 Another form lives in the mantle cavity of the large sea snail, 

 Strombus gigcis. 



Parental Care. — One of the most remarkable instances of paren- 

 tal care by the male is that seen in the sea horse and the pipe fish, 

 where the eggs are carried in a ventral brood pouch by the male. 

 The males of sticklebacks and lump-suckers guard their nests for 

 weeks. The butterfish {Pholis gunnellus) coils around its eggs and 

 guards them. 



Habitat. — The trout lives in water ranging from 20° C. to 1° C. 

 and spawns in October. The common eel of Europe ranges from 



