Data from: Predation on feather stars by regular echinoids as evidenced by laboratory and field observations and its paleobiological implications

Among extant crinoids, the feather stars are the most diverse and occupy the greatest bathymetric range, being especially common in reef environments. Feather stars possess a variety of morphological, behavioral and physiological traits that have been hypothesized to be critical to their success, especially in their ability to cope with predation. However, knowledge of their predators is exceptionally scant, consisting primarily of circumstantial evidence of attacks by fishes. In this study the question whether regular echinoids, recently shown to consume stalked crinoids, also consume feather stars is explored. Aquarium observations indicate that regular echinoids find feather stars palatable, including feather stars known to be distasteful to fish, and that they can capture and eat live feather stars, including those known to swim. Gut content analyses of the echinoid Araeosoma fenestratum (Thomson, 1872), which is commonly observed with large populations of the feather star Koehlermetra porrecta (Carpenter, 1888) in video transects from marine canyons off the coast of France, revealed elements of feather stars in the guts of 6 of 13 individuals. The high proportion of crinoid material (up to 90%), and the presence of articulated crinoid skeletal elements in the gut of A. fenestratum, suggests that these echinoids consumed at least some live crinoids, although they may have also ingested some post-mortem remains found in the sediment. Additionally, photographic evidence from the northeast Atlantic suggests that another regular echinoid, Cidaris cidaris (Linnaeus, 1758), preys on feather stars. Thus in spite of the broad suite of anti-predatory adaptations, feather stars are today subject to predation by regular echinoids and may have been since their Mesozoic origin.在现生海百合（crinoids）类群中，羽星（feather stars）是多样性最高且栖息水深范围最广的类群，尤其常见于礁体生境中。羽星拥有多种形态、行为与生理特征，这些特征被认为是其成功繁衍的关键，尤其是在应对捕食压力的能力方面。然而，学界对其捕食者的认知极为匮乏，现有证据主要来自鱼类攻击的间接佐证。本研究探讨了一类此前被证实可捕食有柄海百合的正形海胆（regular echinoids）是否同样会捕食羽星。水族馆观测结果表明，正形海胆对羽星具有适口性——包括那些被证实对鱼类难以接受的羽星物种，且它们能够捕获并取食活的羽星，包括具备主动游泳能力的种类。对窗格海胆（Araeosoma fenestratum (Thomson, 1872)）的胃含物分析显示，在法国沿海海洋峡谷的视频样带调查中，该海胆常与多孔柯氏羽星（Koehlermetra porrecta (Carpenter, 1888)）形成大规模种群伴生；其13个采样个体中，有6个的胃内含物内检出了羽星组织。胃内含物中海百合组织占比极高（可达90%），且存在关节连接的海百合骨骼结构，这表明这些海胆至少会取食部分活海百合，尽管它们也可能摄食了沉积物中的尸骸残留。此外，东北大西洋的影像证据显示，另一种正形海胆——王冠海胆（Cidaris cidaris (Linnaeus, 1758)）也会捕食羽星。综上，尽管羽星演化出了多样的反捕食适应性特征，但现生羽星仍会遭受正形海胆的捕食，且这种捕食关系或许自羽星在中生代起源以来便已存在。