RATE OF GROWTH, AGE AT SEXUAL MATURITY, AND DURATION OF LIFE OF CERTAIN SESSILE ORGANISMS, AT WOODS HOLE, MASSACHUSETTS

Abstract

Although Balanus, Hydroides and Teredo become sexually mature and spawn during their first season when they are only two months old, they spawn most abundantly during their second season when they are one year of age. Each of them spawns several times during the second summer.Bugula, Botryllus and various hydroids, on the other hand, spawn principally before they are two months old and it is doubtful if they ever survive for a full year. Some of the most prolific animals seem not to live more than a year and they owe their great abundance to their production of several generations in a single summer.These characteristics of organisms in a measure account for the abundant life of the sea and of the rapid rehabilitation of certain species after depletion. Although the sessile animals studied do not survive for more than one or two years such animals as Cumingia, Chœtopleura, and Ostrea often live from four to six years and spawn several times each year.The surprising discovery of this study was the great rapidity of growth and early sexual maturity of these organisms.