The study of recent stalked crinoid populations (family: Pentacrinidae), and the accurate data provided by some authors, allow a detailed analysis of bathymetric distribution for the different species of this family in the western Pacific area. Principal morphological variations of the skeleton linked to this factor are examined. Intraspecific polymorphism in regard to external stem morphology and arm organization is considered for numerous species in that geographic province. The number of taxa could be reduced because some of them are probably ecophenotypal and geographical varieties. Species regroupings are proposed for the Pacific area, especially for members of the genus Metacrinus, Stem and arm morphological variations linked to bathymetry, are interpreted in terms of adaptative strategy (r and k selection). Biogeographical repartition of these species is analysed from that point of view. Such an approach has been conducted to examine stalked crinoid species of genera other than Metacrinus, living in other geographical areas (Atlantic Ocean). Taxonomy, paleoecology and biostratigraphy of fossil stalked crinoids must be reconsidered and discussed in the application of these results.