22 MARVELS OF FISH LIFE 



shark and the seal so that they are not easily detected 

 by the little fish, and his chances of surviving would be 

 small were it not that he in his turn is shaded and 

 coloured so as to afford him protection from these 

 enemies. 



In order to describe the various concealing devices 

 found in the fish world, I propose to take six fishes, 

 differently shaped, coloured and marked, and to deal 

 with each in turn ; first, describing how they appear to 

 us when seen out of the water, or in a tank or bowl, and 

 then how they appear to other fish when seen in their 

 natural surroundings. 



Let us start with the dace as an example of silvery- 

 bodied fishes. When seen out of the water the back 

 is dark, the under-surface white, and the sides a silvery 

 colour. When seen in the water fish of this type be- 

 come inconspicuous because of the fact that their bodies 

 are perfect reflectors. 



A dace at the bottom of a dark, deep hole appears 

 almost black, but should this fish swim straight up, 

 his body would exactly reflect the shade and colours of 

 the strata of water he passed through, until at the top 

 he would be seen as a light greenish-blue shimmering 

 form under the surface of the rippling water. If seen 

 amongst dead sedges the dace is yellow, if amongst 

 green weeds he appears to be green, and if the weeds 

 are sufficiently near to his body each stem and leaf is 

 reflected. 



As an illustration of how the dace reflects any par- 



