A novel report of hatching plasticity in the phylum Echinodermata

Hatching plasticity occurs in response to a wide range of stimuli across many animal taxa, including annelids, arthropods, mollusks, and chordates. Despite the prominence of echinoderms in developmental biology and more than 100 years of detailed examination of their development under a variety of conditions, environmentally cued hatching plasticity has never been reported in the phylum Echinodermata. Here we report plasticity in the timing and stage of hatching of embryos of the sand dollar Echinarachnius parma in response to reductions in salinity. Embryos of E. parma increased their time to hatching more than twofold in response to ecologically relevant salinity reductions, while maintaining an otherwise normal developmental schedule. Embryos that experienced the greatest delay in hatching time emerged from the fertilization envelope as four-arm pluteus larvae rather than hatching as blastulae or early gastrulae. Salinity manipulations across multiple male-female pairs indicated high...

孵化可塑性（hatching plasticity）在多种动物类群中会响应广泛的刺激而发生，包括环节动物、节肢动物、软体动物和脊索动物。尽管棘皮动物（echinoderms）在发育生物学中占据重要地位，且人们已在多种条件下对其发育进行了逾百年的详细研究，但在棘皮动物门中从未报道过环境诱导的孵化可塑性。本文报道了沙币（sand dollar）Echinarachnius parma胚胎的孵化时间与阶段可塑性，该可塑性由盐度降低诱导产生。E.parma胚胎在面对生态相关的盐度降低时，孵化时间延长了两倍以上，同时保持了其他方面正常的发育进程。孵化时间延迟最显著的胚胎从受精膜中孵出时为四腕长腕幼虫（four-arm pluteus larvae），而非囊胚（blastulae）或早期原肠胚（early gastrulae）。对多对雌雄个体进行盐度调控实验表明，其具有高度的...