Phylum XIII 



Annelida, Class Polychaeta 



Order polychaeta errantia, Family nereidae 



NEREIS LIMBATA 



Benjamin H. Grave, De Pauw University 



Nereis limbata, which occurs abundantly in Eel Pond at Woods Hole, 

 is the one species in this vicinity which is known to have a distinct and 

 unmistakable lunar periodicity in spawning. Eggs may usually be had 

 in great abundance roughly from the full moon until new moon during 

 all of the summer months and not to any considerable extent at any other 

 time. 



The eggs and spermatozoa are extruded at night from 9 to 10 p.m. as 

 the sexually mature worms swim at the surface of the sea. As the 

 males and females come into contact with each other they are stimulated 

 to expel their gametes vigorously. The stimulus, however, is chiefly 

 chemical rather than physical. At this time in the month the body 

 cavities of the worms are distended with eggs or spermatozoa and after 

 they are expelled nothing but the ghost of a worm remains. 



METHOD OF COLLECTING 



A small dip net and a lantern or flashlight are needed in collecting. 

 The worms are attracted to light and may be dipped up and placed in 

 suitable dishes of seawater. Females should be kept separate from 

 males, otherwise they spawn at once. 



METHOD OF SECURING EGGS 



Select a distended female, place her in a clean dish of seawater, and 

 with scissors cut across her body to allow the eggs to escape. In the 

 same way cut a male in two in a dish containing 25 or 50 cc. of seawater. 

 After washing the eggs once or twice by pouring off the water and re- 

 filling the dish with fresh seawater, add three or four drops of sperma- 

 tozoa and agitate gently. Within five minutes after insemination the 

 eggs extrude a jelly in which they lie embedded. The eggs are thus 



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