16& 



Handbook of N ature-Stttdy 



Stickleback guarding his nest. 

 Drawn from nature. 



THE STICKLEBACK 



Teacher's Story 



THIS is certainly the most sagacious of the 

 Lilliputian vertebrates; scarcely more 

 than an inch in length when full-grown, it 

 gazes at you with large, keen, shining- 

 rimmed eyes, takes your measure and 

 darts off with a flirt of the tail that says 

 plainly, "Catch me if you can." The 

 sticklebacks are delightful aquarium pets 

 because their natural home is in still 

 water sufflcientl}^ stagnant for algse to 

 grow luxuriously; thus we but seldom 

 need to change the water in the aquari- 

 um, which, however, should be well 

 stocked with water plants and have gravel 

 at the bottom. 



When the stickleback is not resting he 

 is always going somewhere and he 

 knows just where he is going and what he 

 is going to do, and earthquakes shall not 

 deter him. He is the most dynamic 

 creature in all creation, I think, except perhaps the dragon fly, and 

 he is so ferocious that if he were as large as a shark he would destroy all 

 other fishes. Place an earthworm, cut into small sections, in the aquari- 

 um and while each section is wriggingly considering whether it may be 

 able to grow both ends into another worm , the stickleback takes hold 

 with a will and settles the matter in the negative. His ferocity is 

 frightful to behold as he seizes his prey and shakes it as a terrier does a rat. 

 Well is this fish named stickleback, for along the ridge of its back are 

 sharp, strong spines— five of them in our tiny, brook species. These 

 spines may be laid back flat or they may be erected stiffly, making an 

 efficient saw which does great damage to fish many times larger than the 

 stickleback. When we find the minnows in the aquarium losing their 

 scales we may be sure they are being raked off by this saw-back ; and if 

 the shiner or sunfish undertakes to make a stickleback meal, there is 

 only one way to do it, and that is to catch the quarry by the tail, since he is 

 too alert to be caught in any other way. But swallowing a stickleback 

 tail first is a dangerous performance, for the sharp spines rip open the 

 throat or stomach of the captor. Dr. Jordan says that the sticklebacks 

 of the Puget Sound region are called "salmon killers" and that they well 

 earn the name; these fierce midgets unhesitatingly attack the salmon, 

 biting off pieces of their fins and also destroying their spawn. 



As seen from the side, the stickleback is slender and graceful, pointed 

 like an arrow at the front end, and with the body behind the dorsal fin 

 forming a long and slender pedicel to support the beautifully rounded tail 

 fin. The dorsal fin is placed well back and is triangular in shape; the 

 anal fin makes a similar triangle opposite it below and has a sharp spine 

 at its front edge. The color of the body varies with the light; when 

 floating among the water weed the back is greenish mottled with paler 

 green, but when the fish is down on the gravel it is much darker. The 

 lateral line is marked by a rather broad silver stripe. 



