180 Phylum Bryozoa 



Attached or enclosed statoblasts, hibernacula, and colonies may be ob- 

 tained by scraping with a scalpel or sharpened spatula the under side of 

 rocks, lily pads, submerged objects such as boards and rubbish, floating 

 objects such as sticks and logs, leafy aquatic vegetation such as Vallis- 

 neria, Elodea, Potamogeton, Ceratophyllum, Myriophyllum, or Scirpus, 

 and by scraping shells of Unionidae, Astacus (Abricossoff, 1925) and cer- 

 tain tortoises (Annandale, 1912). Records exist for Bryozoans from 

 various depths. Hand collecting is resorted to in the shallows, but at 

 depths beyond three feet the use of double rakes or dredge is necessary. 



Some of the enemies of Bryozoa which may occur in the collections and 

 which should be carefully excluded, are planarians, various gastropods, 

 insect larvae such as chironomids and caddis worms (Hydropsyche, 

 et al.), oligochaete worms, small crustaceans, and arachnids. 



The problem of culturing freshwater Bryozoans has been a rather 

 difficult one. They are very voracious. They feed upon diatoms, 

 desmids, Oscillatoria, Ciliata, Flagellata, some rhizopods (Arcella), small 

 rotifers, etc. Marcus mentions the following forms as of use in feeding 

 Bryozoa: Euglena, Colpoda, and Chlamydomonas. Brown has been 

 successful in using "Geha" fish food, size 000, in culturing Plumatella, 

 keeping the colonies alive and reproducing for four weeks. 



In culturing Bryozoa shallow dishes or finger bowls should be used if 

 one wishes to observe the organisms very frequently. In larger aquaria 

 they may not be easily examined. The water in the finger bowls should 

 be replaced every 2 or 3 days with fresh pond water or with tempered tap 

 water. The following diets were tried out on Lophopodella carteri and 

 found to be unsuccessful: Paramecia, Euglenae, green algae, dried and 

 powdered Elodea, Vallisneria, algae, malted milk, nutritive broth (de- 

 hydrated), and fish food (not powdered). As a last resort, greenhouse 

 water which contained a great amount of organic debris or detritus was 

 tried. This was collected from around the stems and bases of large 

 aquatic plants which had been planted in the greenhouse tanks. Some of 

 the mud and decaying vegetation at the base of the plants was included. 

 Planaria, chironomids and other offenders were removed from the culture 

 as far as possible. The debris was removed and new material added 

 every two or three days. This proved to be an ideal medium for rearing 

 colonies. Lophopodella colonies collected in Lake Erie in August and 

 September, 1932, and cared for in the laboratory released statoblasts in 

 October and November. These statoblasts hatched in November, De- 

 cember, January, and February, giving rise to small colonies. These new 

 colonies gave rise to statoblasts in March and April. Some of these 

 statoblasts germinated in April (1933). The culture dishes were kept 

 in the laboratory under ordinary room conditions of light and tempera- 

 ture (approximately 22 C). 



