BIOLOGY AND NATURAL HISTORY 101 



and animals which lived in the upper few feet of the waters in which the 

 menhaden lived during its annual inshore migrations. 



The menhaden is an indiscriminate and non-selective feeder, whose dietary- 

 consists of whatever of suitable size the waters in a given locality and at a 

 given time afford. A close parallel, both as to quality and quantity, was 

 found between the stomach contents of the menhaden and the contents 

 of nets towed in the waters from which the fish were taken. Although the diet 

 varied from place to place and from time to time (night or day) , the food 

 consisted of small annelids, sometimes ^ inch long, rotifers, small Crustacea, 

 amphipods, schizopod shrimp, ostrocods, peridinia, diatoms, foraminifera, 

 and several larval forms. Ordinarily diatoms and small Crustacea predom- 

 inated as would be expected, since they are the most plentiful members of 

 the microscopic pelagic life. In this respect the menhaden is different from 

 most of the fish in the sea. Its catholic and non-discriminating taste distin- 

 guishes the menhaden as strongly exceptional, if indeed not unique, among 

 the fishes of the sea. Most fishes exercise a certain selectivity in eating, chang- 

 ing their diet from season to season and from place to place. Among the 

 pelagic feeders, the mackerel and the herring, the latter a close relative of 

 the menhaden, are strongly selective, the herring often disappearing from 

 waters in which its desired food is not present. Cheng (1941) compares the 

 herring to the menhaden in this respect, pointing out that the herring, "unlike 

 the menhaden, selects its food by individual acts of capture"; and Lebour 

 (1920) has demonstrated the highly selective feeding habits of fishes. 



MECHANISM OF OBTAINING FOOD. The menhaden strains these microscopic 

 and near-microscopic plants and animals from the sea water by means of a 

 very efficient sieve located in its mouth and throat. The gills of the menhaden 

 are equipped with a set of comb-like, long, slender gill-rakers, lying parallel 

 and very close together, each raker itself being a comb of still finer teeth. 

 The entire mouth cavity is coated with mucus. As the fish swims through the 

 water, his mouth open and opercula distended, the water, laden with micro- 

 scopic plants and animals, passes through this fine sieve. The animals and 

 plants become entangled, are coated with mucus, and then are swallowed or 

 forced down the throat into the stomach. This straining device is as efficient 

 as any devised by man. Bigelow (1928) aptly compares the filtering mech- 

 anism of the menhaden with similar apparatuses of other fish, ". . . nor is 

 any other local species possessed of a filtering apparatus comparable to that 

 of the menhaden for fineness and efficiency." 



The menhaden feeds by swimming rapidly through the water with mouth 

 agape, literally funneling the water through its mouth and forcing it through 

 its pectinated or comb-like gills. Schroeder (in Hildebrand and Schroeder, 

 1928) in his field notes recorded aboard the "Fish Hawk" graphically de- 

 scribes the feeding habits of the menhaden as follows: 



