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，尤其在礁相环境中极为常见。羽星具备多种被认为对其演化成功至关重要的形态、行为与生理特征，尤其是应对捕食压力的能力。然而，目前学界对其天敌的认知极度匮乏，现有证据仅以鱼类发起攻击的间接线索为主。本研究针对一类近期被证实可捕食有柄海百合的规则海胆（Regular echinoids）是否同样会捕食羽星展开探究。水族箱观测结果表明，规则海胆对羽星具有适口性——包括那些被证实对鱼类而言难以下咽的羽星类群，且它们能够捕获并取食活的羽星，其中甚至包含具备主动游泳能力的种类。对网格海球胆（Araeosoma fenestratum，Thomson, 1872）的肠道内容物分析显示：在法国外海海底峡谷的视频样带中，该海胆常与大量扁平柯氏羽星（Koehlermetra porrecta，Carpenter, 1888）形成密集伴生种群；其13个采集个体中，有6个的肠道内检出羽星组织成分。肠道内海百合类组织占比最高可达90%，且存在关节化的海百合骨骼结构，这提示这些规则海胆至少会取食部分活海百合，尽管它们也可能同时摄食了沉积物中存在的生物死后遗骸。此外，东北大西洋的影像证据显示，另一种规则海胆——长刺海胆（Cidaris cidaris，Linnaeus, 1758）也会捕食羽星。由此可见，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规则海胆的捕食，且这种捕食关系或许自羽星在中生代起源以来便已存在。