Data from: 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 variability in hatching time both within and among clutches, suggesting significant intraspecific variation in developmental responses to salinity.

孵化可塑性可响应多种刺激信号，广泛存在于诸多动物分类群中，涵盖环节动物门（Annelida）、节肢动物门（Arthropoda）、软体动物门（Mollusca）以及脊索动物门（Chordata）。尽管棘皮动物门（Echinodermata）在发育生物学领域占据重要地位，且已有百余年针对其在多种实验条件下发育过程的细致研究，但此前从未有关于棘皮动物门存在环境诱导孵化可塑性的报道。本研究报道了沙钱海胆（Echinarachnius parma）胚胎的孵化时间与孵化阶段可塑性，该可塑性响应盐度降低的环境刺激。当暴露于生态相关的盐度降低胁迫时，该物种胚胎的孵化时长可延长两倍以上，且其余发育进程均维持正常。孵化时长延迟最显著的胚胎，并非以囊胚或早期原肠胚阶段从受精膜破壳孵化，而是以四腕长腕幼虫的形态脱出受精膜。对多组雌雄配对个体开展的盐度操控实验结果显示，同一卵群内部以及不同卵群之间的孵化时间均存在较高变异，表明该物种对盐度的发育响应存在显著的种内差异。