FIELD BOOK OF PONDS AND STREAMS 



out appendages but brightly colored by the blood, red with 

 haemoglobin as it is in fishes. Their backs are so transparent 

 that it is often possible to see the beating of the long tubular 

 heart. 



In all species of fairy shrimps females appear to be much 

 more abundant than males, in some kinds no males are known 

 and the young develop from eggs which have never been fer- 

 tilized by male cells. IMating fairy shrimps swim about to- 

 gether, the male holding the female to his ventral side with the 

 peculiar claspers which are parts of his antennae modified as 

 mating organs, the most conspicuous features on the face of 

 the male fair}^ shrimp (Fig. 123, 2). Just behind his gills, on 

 the eleventh segment of the body, are the tube-like append- 

 ages by which he transfers the sperm cells to the fem.ale. In 

 Euhranchipus (Fig. 123, i) the female carries the eggs in her 

 conspicuous brood-pouches, sometimes until the young 

 shrimps hatch. 



Habitat, season. — Fairy^ shrimps live in small, often tem- 

 porary ponds, particularly in cold waters, and are widely dis- 

 tributed over the United States. They swim on their backs 

 through the ice-cold waters of early spring pools but their 

 coming is fraught with uncertainty. For five years they may 

 come round like the seasons, then they may not appear at all 

 no matter how right the conditions and in spite of the fact 

 that earlier they have been too common to be appreciated. 



While they are active and full of vitality in the spring they 

 produce resting eggs which fall to the bottom and lie dormant 

 in mud either wet or dried. These eggs can endure drjang 

 for long periods ; some even appear to need drjdng before they 

 will hatch. Eggs of fairy shrimps kept in dried mud are re- 

 ported to have developed when they were put into water after 

 a drying period of fourteen years. 



Food. — Fairy shrimps live on microscopic organisms — the 

 protozoans, floating diatoms, and other algae — which popu- 

 late the open waters of ponds. These are gathered in a sort 



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