The diet of the dorid nudibranch Platydoris argo was studied in relation to prey availability, and under different environmental conditions to evaluate richness, evenness, and plasticity of its diet. In order to assess the availability of possible prey, the sponge assemblage at two different habitats was characterized. The results showed that P. argo is a relatively specialized benthic carnivore, feeding exclusively on spiculated demosponges. However, it has a relatively polyphagous diet (16 prey-species) and adapts well to contrasting patterns of prey availability at different sites. At the location with lower sponge diversity, the diet of P. argo included more prey categories, was more diverse, and less selective (lower dietary evenness), foraging preferentially on the most frequent resource, Stylopus dujardini. In contrast, at a station with a clearly more diverse and abundant sponge assemblage, the diet was more selective, and Phorbas tenacior was its principal component. Despite its trophic plasticity, P. argo displayed a specialized pattern of resource exploitation in terms of niche breadth within a given habitat. Foraging was focussed on one preferred prey (which changed from one habitat to another) as indicated by the significant positive selection indexes (S. dujardini = +0.29, P. tenacior = +0.74). The revision of quantitative data on the diet of so-called 'sponge eating dorids' indicates the existence of a more specialized guild of 'spiculated demosponge eating dorids'. Most species revised are 'non-stereotyped specialist', which indicates that they have a polyphagous and plastic diet but only exploit one or few main prey species in each habitat. However, obligate specialists, with a monophagous (or rather oligophagous) diet also seem to be present.

中文翻译：

---

PLATYDORIS ARGO（腹足纲：裸鳃亚目）的饮食和吃海绵的DORIDS的饮食专业

研究了 Dorid nudibranch Platydoris argo 的饮食与猎物可用性的关系，并在不同的环境条件下评估其饮食的丰富度、均匀度和可塑性。为了评估可能的猎物的可用性，对两个不同栖息地的海绵组合进行了表征。结果表明，P. argo 是一种相对特化的底栖食肉动物，专门以带刺的海绵体为食。然而，它的饮食相对多食（16 种猎物），并且能很好地适应不同地点猎物供应的对比模式。在海绵多样性较低的位置，P. argo 的饮食包括更多的猎物类别，更加多样化，选择性更少（饮食均匀度较低），优先在最常见的资源 Stylopus dujardini 上觅食。相比之下，在一个海绵组合明显更加多样化和丰富的站点，饮食更具选择性，Phorbas tenacior 是其主要成分。尽管具有营养可塑性，P. argo 在给定栖息地内的生态位宽度方面表现出特殊的资源开发模式。如显着的正选择指数（S. dujardini = +0.29，P.tenacior = +0.74）所示，觅食集中在一种首选猎物（从一个栖息地变为另一个栖息地）。对所谓的“吃海绵的 dorids”饮食定量数据的修订表明存在一个更专业的“吃毛海绵的 dorids”行会。大多数修订的物种是“非定型专家”，这表明它们以多食性和塑料性为食，但在每个栖息地只捕食一种或几种主要猎物。然而，似乎也存在专食（或者更确切地说是寡食）饮食的专职专家。