From competent larva to exotrophic juvenile:: a morphofunctional study of the perimetamorphic period of Paracentrotus lividus (Echinodermata, Echinoida)
From competent larva to exotrophic juvenile:: a morphofunctional study of the perimetamorphic period of Paracentrotus lividus (Echinodermata, Echinoida)
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DOI：
10.1007/s004350050054
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发表时间：
1998-03-01
期刊：
影响因子：
1
通讯作者：
Jangoux, M
中科院分区：
文献类型：
--
作者：
Gosselin, P;Jangoux, M
鹅毛旁胚的近变质期为8 ~ 12天。它从幼虫能力的获得开始，包括形态的变化（蜕变）和幼虫后的内营养化生活，并随着外营养化幼鱼的出现而停止。所有主要的幼虫后附属物都已经出现在有能力的幼虫身上，它们要么被归为棘刺样雏形（终板、早期棘和初级足），要么分散在幼虫被皮中（生殖板和无梗蒂）。有能力的幼虫表现出特殊的行为，使它们靠近基质。后者是通过幼虫前庭孔突出的初级足来检验的。初级足部是被剥夺壶腹的感觉分泌附属物。它们能够附着在基质上，以允许棘刺样雏形的外翻（即变态）和幼虫后的基质粘附。特定的刺由幼虫后携带；这些是多裂的不可移动的附属物，形成了一种保护性的盔甲。与幼虫一样，幼虫后的所有特征结构（初级足、多棘和无柄马蒂）都是短暂的，在幼虫后期（初级足）或幼体早期（多棘和无柄马蒂）都是退化的。其他在幼虫后期发育的附属物（如带壶腹的足部、尖刺和球形体）与成虫的附属物相似，并在个体进入幼年期时开始发挥作用。因此，在P. lividus的生命周期中，准变质期似乎是一个完全成熟的时期，想必在任何其他海胆物种的生命周期中也是如此。
The perimetamorphic period in Paracentrotus lividus lasts for 8-12 days. It starts from the acquisition of larval competence, includes the change in form (metamorphosis) and the endotrophic postlarval life, and stops with the appearance of the exotrophic juvenile. All major postlarval appendages already occur in competent larvae being either grouped into the echinoid rudiment (terminal plates, early spines and primary podia) or scattered within the larval integument (genital plates and sessile pedicellariae). Competent larvae show particular behaviour which brings them close to the substratum. The latter is tested by primary podia protruding through the vestibular aperture of the larva. Primary podia are sensory-secretory appendages that are deprived ampullae. They are able to adhere to the substratum in order to allow evagination of the echinoid rudiment (i.e. metamorphosis) and substatum adhesion of the postlarva. Particular spines are borne by the postlarva; these are multifid non-mobile appendages forming a kind of protective armour. Like those of the larva, all characteristic structures of the postlarva (primary podia, multified spines and sessile pedicellariae) are transitory and regress either at the end of postlarval life (primary podia) or during early juvenile life (multifid spines and sessile pedicellariae). Other appendages that develop during postlarval life (i.e. podia with ampulla, point-tipped spines and sphaeridiae) are similar to those borne by the adults and become functional when the individual enters its juvenile life. Thus, the perimetamorphic period appears to be a fully fledged period in the life-cycle of P. lividus, and presumably in the life-cycle of any other sea-urchin species.