Phylum VI 



Nemertea 



METHODS FOR THE LABORATORY CULTURE OF 



NEMERTEANS 



Wesley R. Coe, Yale University 



NEMERTEANS are found under extremely diverse environmental 

 conditions. Many species are strictly littoral, living in the mud and 

 sand, or beneath stones between tide-marks, or in shallow water along the 

 seashore. Others are found upon the sea-bottoms at moderate depths. 

 Still others swim freely suspended as bathypelagic organisms 1,000 meters 

 or more beneath the surface of the great oceans, while a few freshwater 

 species are to be found in pools and streams in all temperate and tropical 

 regions or in water-holding leaves of tropical plants. Several species 

 have acquired terrestrial habits, living in moist earth in tropical or semi- 

 tropical lands, whence they have been accidentally transported to green- 

 houses in all parts of the world. 



The nemerteans have a distinct advantage over many other groups 

 of invertebrates for laboratory culture because, although they are essen- 

 tially carnivorous, the individuals of many of the small littoral species 

 are able to live for a year or more without other food than that which 

 may be obtained from their own tissues. Several of these may reproduce 

 asexually in the meantime, but sexual reproduction does not occur under 

 such conditions. 



LITTORAL SPECIES 



The slender Lineus socialis of the Atlantic coast, or the similar 

 L. vegetus of the Pacific coast, found beneath stones between tide-marks, 

 is easiest to culture since it requires only a covered dish of seawater with 

 a bottom layer of pebbles and sand mixed with a little mud, freshly 

 brought from the nemeateans' natural habitat. This material will 

 supply the necessary small Crustacea, nematodes, and other small in- 

 vertebrates to keep the animals in good condition for a year or two if 

 the water lost by evaporation is replaced from time to time. Asexual re- 

 production will occur frequently and egg clusters may be deposited in 

 late winter or early spring, but only if the water is kept below 15 C. 



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