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（hatching plasticity）广泛存在于多个动物类群中，可响应多种刺激因素，涵盖环节动物（annelids）、节肢动物（arthropods）、软体动物（mollusks）与脊索动物（chordates）。尽管棘皮动物在发育生物学领域占据重要地位，且其在多种实验条件下的发育过程已被细致探究百余年，但目前棘皮动物门（phylum Echinodermata）中尚未见环境诱导孵化可塑性的相关报道。本研究首次报道了沙钱（Echinarachnius parma）胚胎的孵化时间与孵化阶段可塑性，其可响应生态相关水平的盐度降低。在该条件下，E. parma的胚胎孵化时间延长了两倍以上，同时其余发育进程仍保持正常节律。那些孵化延迟程度最高的胚胎，会以四腕长腕幼体（four-arm pluteus larvae）的形态挣脱受精膜（fertilization envelope）而出，而非以囊胚（blastulae）或早期原肠胚（early gastrulae）的阶段完成孵化。对多组雌雄配对个体开展的盐度操控实验显示，卵群（clutches）内部以及不同卵群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变异（intraspecific variation）。