Family GASTEROSTEIDAE 



THE STICKLEBACK FAMILY 



In this family of fishes the body is somewhat compressed and the 

 caudal peduncle, or portion before the caudal fin, is very slender. TRe 

 head is medium sized. The mouth is moderate; the lower jaw projects 

 beyond the upper. The maxillary is bent and overlaps the premaxillary 

 at the corner of the mouth. The jaws are set with sharp, even teeth, and 

 the upper jaw is protractile. There are no true scales. The dorsal fin is 

 preceded by several free spines. The branchiostegal rays number 3. The 

 ventral fins each have a stout spine, and the pectoral fins are inserted 

 far back. The air bladder is simple. A small number of pyloric caeca are 

 present. 



The sticklebacks are small, carnivorous fishes of which several genera 

 and species are found in both fresh and salt waters. Most or all of 

 them build nests. They are represented in Minnesota by two genera 

 and two species. 



Key to Common Species of Family GASTEROSTEIDAE 

 Dorsal fin preceded by 4-6 free spines. 



.Brook Stickleback, Eucalia inconstans (Kirtland) 



Dorsal fin preceded by 8-1 1 free spines 



Ninespine Stickleback, Pungitiu^ pimgitivs (Linnaeus) 



GENUS En c alia Jordan 



This genus contains only one species, distributed from Kansas to 

 New York and throughout the Great Lakes region. 



BROOK STICKLEBACK 



Eucalia inconstans (Kirtland) 



The brook stickleback (Figure 55) is a graceful little fish mottled in 

 colors that vary from brown to black, with the under parts usually 

 lighter; there is some red on the anterior parts of the spring males. The 

 body is somewhat elongate and moderately compressed; the portion 

 before the caudal fin is very small. No scales are present. The gill- 

 membranes are somewhat free posteriorly; the gill-rakers are short. No 

 ridge, or keel, is present along the caudal peduncle. The head is con- 

 tained 3.5 times in the length, the depth 4 times. The dorsal fin has 4 

 or 5 free spines anteriorly and 9 or 10 soft rays posteriorly. The anal 

 fin has 1 spine and 9 or 10 soft rays. This species seldom exceeds 2 1/2 

 inches in length. 



<i55 



