What have been brought together in these volumes are works represent­ ing a variety of modern quantitative studies on a select group of marine organisms. Some of the species studied here represent basic biological ex­ perimental subjects-in some cases, marine versions of the white rat and pigeon-that are being used for a wide range of studies. Other species studied were virtually unknown as experimental animals. The authors have studied their animals in considerable depth, often in both the field and the laboratory. It is this cross reference between real life and the artificial but controlled conditions of the laboratory which gives us the necessary understanding, and ultimately the means, for improving our rapidly deteriorating environment, a must for man's survival, maintenance, and improvement of the quality of living standards. A direct outgrowth of a AAAS symposium entitled "Recent Advances in the Behavior of Marine Organisms" held in December 1966, these vol­ umes include a reasonable balance between review and original unpublished research. Of the many persons who have made these volumes possible, we wish to especially thank Nancy Fish, Lois Wino, Mabel Trafford, and Deborah Brennan. The latter two accomplished most of the final editorial work. The personnel of Plenum Press were cooperative in all aspects of our rela­ tionship. Only the two editors are responsible for defects in the volumes. We believe the papers presented are significant and will be of importance to members of the scientific community.