Reproductive cycle and sex hormones in the feather star Antedon mediterranea

In the recent decades, the importance of echinoderm endocrinology has increased because of the use of echinoderms as models for aquatic ecotoxicology and due to their evolutionary closeness to chordates. Nonetheless, apart from asteroids and echinoids, there is limited information available on the reproductive physiology of echinoderm groups, particularly crinoids. This investigation focused on the reproductive cycle of Antedon mediterranea and was intended to elucidate the reproductive pattern occurring in this species. We observed spawning throughout the year, though there were preferential months. The sex ratio was biased in favour of females. Possible correlations between steroid level variations and gonad maturity were also evaluated: testosterone and 17β-estradiol mean levels were higher at the beginning of gametogenesis and during vitellogenesis, suggesting their possible involvement in nutrient supply for developing gametes. This study should stimulate further work on steroids and steroid derivatives as ancestral hormones characteristic of the animal kingdom.