
FOOD AND FEEDING 

paired and one central single eye. It has two pairs of threadlike an- 
tenn. Under the shell there are 60 pairs of gilled 
legs, of which the first pairs are developed into anten- 
nze-like feelers. It swims on the back and steadily 
moves through the water by rapid undulating strokes 
ofthe legs. The periodic appearance of this Crustacean 
may be due to the fact that the eggs must be subjected 
to a period of incubation in the dry earth. The food 
consists of water animalculz and decaying vegetation. 
It is the larvee and young of these Branchiopods 
which constitue the food of the mature goldfish, 
the adult being of too large size to be readily 
taken. It is principally the Crustaceans of the follow- 
ing sub-order Cladocera which constitute their live food. 
SuB-ORDER CLADOcERA. Compressed body small, indistinctly seg- 

FIG. 65. Apus cancriformus. 
Greatly enlarged. 
mented, enclosed in a bivalve carapace, four or six swimming feet, and the 
posterior antennz developed as longer swimming feet. The most general 
forms are Daphnia, Polyphemus and Leptodora. Daphnella, Sida and 
Ciriodaphnia also belong to this sub-order. 
DapuniaA. Fig. 66. Four or five species of Daphnia, known to the 
goldfish breeder by their light green, dark green, red and reddish colors, 
abound at different seasons in almost every still or stagnant water. Their 
size is from .75 to 1.5 millimeters. The segmentation 
of the body is imperfect, the Crustacean being covered by 
afolded carapace. The head is distinct and the abdomen 
is turned downward and isin constant movement. The 
long antennez are moved at longer or shorter intervals, 
making the progress a series of rapid starts and stops. 
Between the abdomen and the carapace of the female 
is a large brood pouch in which the eggs are stored 
and hatched and the larve only make their escape 
when they have reached the free-swimming stage. The 

FIG. 66. Daphnia pulex. paired eyes have fused into a single organ. ‘There are 
ee ee five pairs of swimming legs on the thorax. The re- 
production of the Daphnia is most curious. During the summer the 
female develops spores, which, without fructification by the male, develop 
in the brood pouch to perfect Daphnia in four days, and which, when they 
have become liberated, in a few days reproduce in the same manner. In 
the fall of the year the much smaller males appear and the sexual repro- 
duction takes place. Winter eggs are produced, the thick shells of which 
protect them through the cold season. The food of the Daphnia 1s de- 
119 
