The Comparative Reproductive Physiology of Sea Turtles

Abstract

Although the reproductive ecology of marine turtles has been the subject of numerous long-range studies, the reproductive physiology of these unique animals is little known. Recently, however, preliminary anatomical and endocrinological studies have provided a good basis on which to begin to attempt to explain several of their unusual biological systems. New findings related to the anatomy of Chelonia mydas and Lepidochelys olivacea are presented. The female, although having a very massive pair of simultaneously functioning ovaries, appears in most ways very similar to other chelonians. Corpora hemorrhagica, corpora lutea and corpora atretica from active ovaries are briefly described. Ovulation coincides with a luteinizing hormone and progesterone surge. Sperm are probably stored for the season after a single mating period which appears to occur prior to the first ovulation. Males may also cycle and mating as well as nesting are seen as more or less seasonal. The seasonality could be controlled in part by melatonin or other endocrines from the sea turtle's massive pineal complex. A hypothetical model for reproduction is presented in hopes of stimulating interest in physiological approaches to the study of marine turtle reproduction.