1 9 8 Phylum Annelida 



The burrows of Urechis may be distinguished in the following manner: 

 The opening of the burrow varies somewhat in size according to the 

 size of the animal within, but is always smaller than the deeper portions. 

 The diameter of the opening varies from the size of a lead pencil to 

 some twice that size, and is always well smoothed and has a somewhat 

 slick appearance due to the mucus secreted by the animal, and which 

 holds the sand and mud in place. At one or the other of the openings 

 castings usually will be found. These castings are of equal length and 

 smoothly rounded at each end. A casting of average size will be about 

 i mm. in diameter and i cm. in length. 



Since Urechis is one of the few animals which has two openings to its 

 burrow, one may feel quite sure that it is a burrow of this animal, if, 

 after locating two openings about 30 inches apart, one steps quickly on 

 one hole, or jabs a shovel handle into it, and the water squirts out the 

 other hole. This also locates the animal underground in so far as it must 

 be somewhere between the two openings. This test may not be repeated, 

 for, after being disturbed, Urechis will tightly block the burrow. 



In bringing living specimens of Urechis to the laboratory it is necessary 

 that they be kept cool to prevent harm both to the animals themselves 

 and to the sex products that they contain. If they are to be transported 

 for any distance the container in which they are carried should be packed 

 in ice. By using ice I have transported them a distance of 250 miles 

 without ill results. Males and females should be segregated by testing, 

 and kept in separate aquaria so that when used in the future the par- 

 ticular sex needed may be known readily. 



MAINTENANCE IN THE LABORATORY 



If the animals are to be used for only a short period of time they 

 may be left in the bottom of an aquarium with a good supply of running 

 salt water. However, if they are to be kept for longer periods of time it 

 is much better to keep them in glass tubes. These tubes may be bent 

 U-shaped to simulate their natural burrows, in which case the animals 

 may be kept for years. But even straight tubes in which they may be 

 confined by corking the ends with single-holed corks will keep the ani- 

 mals in good shape for a much longer period than usually will be the 

 case when they are kept free in the aquarium. In the U-shaped tube 

 they will feed and carry on all the activities of their natural habitat. In 

 general they will not feed in a straight tube, although an occasional 

 individual may do so. The glass tubing in which they are confined 

 should be of ample dimensions, as when one is handling the worms they 

 lose their respiratory water and may be confined in a space much smaller 

 than they actually require. Especially in the southern limits of their 

 range Urechis is often spawned out in summer, so that in order to insure 



