208 The Life Story of the Fish 



out of the wake of the boat, and makes it skip over the 

 surface in simulation of a flying fish. 



In this connection, the natural relation between the flying 

 fish and the tuna is of interest. The tuna is, as we know, one 

 of the fastest of fishes: it can make at least thirty miles an 

 hour. In the water, the flying fish can attain no such speed, 

 but it has been estimated that in the air it sometimes glides 

 more than one thousand feet at a rate of forty miles an hour. 

 When it does this it leaves the tuna far behind. Therefore a 

 single flying fish can escape a single tuna if it makes a good 

 flight J but if it makes ^ poor one, or if it is surrounded by a 

 school of tuna, it has little chance. 



One other feature of interest in connection with the 

 tuna's speed is its high body temperature. Unlike most fish, 

 its insides are consistently six to eight degrees warmer than 

 the surrounding water. The explanation is thought to lie in 

 the smallness of its viscera. This great big bouncing fish is 

 almost all muscle, with its stomach and intestines tucked 

 away in a comparatively tiny space. To furnish the energy 

 necessary for the animal's swift propulsion through the 

 water, a great amount of food must be consumed. With its 

 small capacity, the only way to accomplish this is to pass the 

 food through the digestive organs with great rapidity. In 

 other words, the fuel must be burned very fast, and the 

 result is a high body temperature. 



On our Atlantic coast, the tuna follows the example of 

 many vacationists, and goes to New England for the sum- 

 mer. On account of the immense size which it reaches in 

 these waters — one thousand pounds is not uncommon, and 

 a ten-foot fish weighing sixteen hundred pounds has been 

 recorded — the New England fishermen used to call it the 

 "horse mackerel," and for a long time had little regard for it 

 as a food-fish. More recently they have come to realize that 



