The North Atlantic deep-water polynoid worm Neopolynoe chondrocladiae is involved in an exceptional symbiotic relationship with two hosts: the carnivorous sponges Chondrocladia robertballardi and Chondrocladia virgata. While this is an obligate symbiotic relationship, its real nature is unclear. We used a multidisciplinary approach to narrow down the type of symbiotic relationship between symbiont and hosts. Molecular connectivity analyses using COI and 16S suggest that N. chondrocladiae has high potential for dispersal, connecting sites hundreds of kilometres apart, likely aided by oceanographic currents. Microbial analyses on different anatomical parts of five Chondrocladia species suggest that the presence of the worm in C. robertballardi does not affect the microbiome of the sponge. MicroCT analysis on N. chondrocladiae show that it has dorsally oriented parapodia, which might prevent the worm from getting trapped in the sponge. A faecal pellet recovered from the worm suggests that the polynoid feeds on the crustacean prey captured by the sponge, something corroborated by our stable isotope analysis. Light and confocal microscopy images suggest that N. chondrocladiae elytra produce bioluminescence. We propose that the worm might use bioluminescence as a lure for prey (increasing the food available for both the sponge and the polynoid) and thus fuelling a mutualistic relationship.

中文翻译：

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与敌人同睡：揭开鳞虫新孢子虫（Annelida：Polynoidae）与其食肉海绵宿主之间的共生关系

北大西洋深水多角型蠕虫Neopolynoe软骨线虫与以下两个宿主有特殊的共生关系：食肉海绵软骨球菌（Condrocladia robertballardi）和中华线虫（Condrocladia virgata）。虽然这是一种专心的共生关系，但其真实性质尚不清楚。我们使用了多学科的方法来缩小共生体与宿主之间的共生关系类型。使用COI和16S进行的分子连通性分析表明，软骨克雷德菌具有很高的扩散潜力，可能相隔数百公里连接地点，这可能受到海洋流的帮助。五个软骨纲不同解剖部位的微生物分析的物种表明，蠕虫在罗氏衣原体中的存在不会影响海绵的微生物组。MicroCT对软骨念珠菌的分析表明，它具有背向伪足，可以防止蠕虫被困在海绵中。从蠕虫中回收的粪便颗粒表明，no虫以海绵捕获的甲壳类动物为食，我们的稳定同位素分析证实了这一点。光学和共聚焦显微镜图像表明，鞘翅目猪笼草（N. chondrocladiae elytra）产生生物发光。我们建议蠕虫可以利用生物发光作为猎物的诱饵（增加海绵和sponge虫的食物），从而助长了相互关系。