Gastropods from the family Eulimidae are known as parasites of all living classes of echinoderms. Here we determine the trophic relationships between ectoparasitic eulimids Echineulima mittrei and their hosts, sea urchins Diadema setosum in Vietnam. Stable isotope analysis showed the differences in δ13C and δ15N saturation in echinoderms tissues. The eulimids’ muscle and gonad tissues have the same carbon isotopic composition as the gonads of the hosts; however, they are more saturated with heavy nitrogen isotopes. The isotopic signatures indicate that ectoparasites feed on the fatty tissues of their hosts, especially gonads. Moreover, we suggest selective feeding in eulimids and possible migration of parasites’ proboscis among different host gonads and probably changes in the metabolism of parasites.

中文翻译：

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寄生腹足动物 Echineulima mittrei (Gastropoda: Eulimidae) 和海胆 Diadema setosum (Echinoidea: Diadematidae) 宿主之间的饮食关系

Eulimidae 科的腹足动物被称为棘皮动物所有活类的寄生虫。在这里，我们确定了外寄生物 Eulimids Eulimids Echineulima mittrei 与其宿主，越南的海胆 Diadema setosum 之间的营养关系。稳定同位素分析表明，棘皮动物组织中 δ13C 和 δ15N 饱和度存在差异。eulimids 的肌肉和性腺组织与宿主的性腺具有相同的碳同位素组成；然而，它们的重氮同位素更加饱和。同位素特征表明外寄生虫以宿主的脂肪组织为食，尤其是性腺。此外，我们建议在 eulimids 中进行选择性喂养，寄生虫的长鼻可能会在不同宿主性腺之间迁移，并且可能会改变寄生虫的代谢。