In the ophioplutei of brittle stars, the posterior coeloms are commonly assumed to be produced by a transverse fission of the initially formed coeloms; but in ophioplutei of Ophiopholis aculeata, the posterior coeloms first appear separately as aggregations of mesenchyme-like cells near the base of the posterolateral arms. Initiation of posterior coeloms was similar in ophioplutei of another family and may be similar in diverse ophiuroids. Initiation is easily missed without frequent observations. Early interpretations that diagrammed a fission of the first-formed coeloms appear to have influenced later authors for more than a century. Growth of posterior coeloms from a small initial size facilitated observations of developmental plasticity in growth of coeloms relative to that of larval arms. This plasticity, as observed in echinoplutei of echinoids, is relatively greater growth of a ciliary band for food capture when food is scarce and relatively greater growth of juvenile structures that will function after metamorphosis when food is abundant; however, juvenile structures develop extensively as a rudiment within the echinopluteus prior to settlement and metamorphosis, whereas in ophioplutei there is little development of juvenile structures until metamorphosis. In ophioplutei there is, therefore, less scope for shifting growth to structures that gain function after metamorphosis. Nevertheless, we found that when ophioplutei were at higher concentrations of food, the growth of the posterior coeloms was greater relative to the growth of the larval arms. Developmental plasticity in allocation of growth to larval and postlarval equipment can occur despite disparate patterns of development.

中文翻译：

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Ophiuroid（脆性星）后体腔的起始及其发育的可塑性

在脆性星的蛇尾藻中，后体腔通常被认为是由最初形成的体腔横向裂变产生的；但在 Ophiopholis aculeata 的蛇尾藻中，后体腔首先单独出现，作为靠近后外侧臂基部的间充质样细胞的聚集体。后体腔的开始在另一个科的蛇尾鱼中是相似的，并且在不同的蛇尾鱼中可能是相似的。如果不经常观察，很容易错过启动。描绘最初形成的体腔裂变的早期解释似乎影响了后来的作者一个多世纪。后体腔从小初始尺寸的生长有助于观察体腔相对于幼虫臂生长的发育可塑性。这种可塑性，正如在棘皮动物的棘头动物中所观察到的那样，当食物稀缺时，用于捕获食物的纤毛带的生长相对较大，而当食物丰富时，在变态后将起作用的幼体结构相对较大地生长；然而，幼体结构在定居和变态之前作为棘龙内的雏形广泛发育，而在蛇腹中，幼体结构在变态之前几乎没有发育。因此，在蛇尾藻中，将生长转移到在变态后获得功能的结构的空间较小。然而，我们发现，当蛇麻属的食物浓度较高时，后体腔的生长相对于幼虫臂的生长更大。