214 Phylum Arthropoda 



METHODS FOR CULTURING DAPHNIA 



Arthur D. Hasler, U. S. Bureau of Fisheries 



i. Algae Method, a. Run tap water into battery jars or butter tubs 

 and allow to stand for 24 hrs. for the purpose of getting rid of air bubbles; 

 otherwise the water-fleas adhere to these and are carried to the surface 

 where they soon perish. 



b. Add sufficient algae to tinge the water slightly green and inoculate 

 with Daphnia. 



c. The alga Coccomyxa simplex may be cultured in large quantities 

 by a method developed by H. Schomer. When the culture is at its peak 

 it is centrifuged with a Birge-Juday centrifuge and it is this centrifugate 

 that is added to the Daphnia culture. The algae may be grown in 

 battery jars. The Schomer medium consists of: 



This method surpasses any I have tried in bringing about maximum 

 rate of reproduction. 



2. Yeast Method (Modified from Bond's), a. Same as (a) above. 



b. Make a thick suspension of moist Star or Fleischmann's yeast in a 

 flask by shaking chunks vigorously until a suspension forms; then add 

 the suspension to the culture until the water is slightly milky. When the 

 water-fleas have cleared it, add the same amount again. Water should 

 be completely changed once a month and the crop seined often to prevent 

 crowding. Aeration is not necessary, but the maximum reproductive 

 rate is reached with aeration. Stirring once a day is sufficient to keep 

 the culture going satisfactorily. 



c. Augmenting the yeast diet with the algae as described above is 

 recommended. If the cultures are in good light, algae generally grow 

 on the sides. They may be scraped off the walls with a razor blade and 

 then broken up by stirring. These serve well to augment the yeast diet. 

 One may also add about a teaspoonful of dry sheep manure per 4 gal. 

 every two weeks. The addition of these substances gives D. magna, for 

 example, the natural red color, whereas if they are raised on yeast alone 

 their color is almost white. 



3. Bant a' s Method. [See p. 208.] This method gives very satis- 

 factory results. I raised Daphnia for 9 months in total darkness, using 

 culture water made according to his directions. 



4. Sheep Manure method, a. Let water stand in suitable containers 

 24 hours. 



b. To every gallon of water, add 1 teaspoonful of dry sheep manure, 



