An oviposition alarm system for the crab Eriocheir japonica

This paper describes an electronic system for obtaining mature, unfertilized eggs from decapods. The system was a by-product of the author's many years of research on in vitro artificial fertilization in crabs (brachyurans). Based on the results of multiple tests, the system has proved to be highly utilizable for research involving the use of mature, unfertilized eggs. The greatest advantage of this system is that it saves researchers a tremendous amount of time and trouble, as the collection of mature, unfertilized eggs is an extremely exhausting procedure that requires 24-hour monitoring over a period of days or weeks. Although the system was originally designed for research with the fresh water mitten crab Eriocheir japonica, it can be used with other decapods with slight modifications.