Size-frequency analysis of the echinoid Echinocyamus pusillus from six offshore areas in the southern North Sea and eastern English Channel reveal five distinct cohorts, suggesting a lifespan of five years. In all six individual areas one or more year-groups are absent, due to the unsuccessful recruitment of planktonic larvae to the seabed in some years, giving a false impression of a shorter lifespan. A relatively long lifespan and planktotrophic larval development are remarkable for such a small species, which reaches a maximum test length of 7.3 mm in the area, such traits being more typical of large-sized macrobenthic species. The feeding mode is akin to that of many meiobenthic taxa. The architecture of the test confers exceptional strength and resilience to mechanical perturbation.

中文翻译：

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Echinoid Echinocyamus pusillus 的不规则募集及其对生物学性状分析的意义

海胆的大小频率分析棘球绦虫来自北海南部和英吉利海峡东部的六个近海地区揭示了五个不同的队列，表明它们的寿命为五年。在所有六个单独的区域中，由于浮游幼虫在某些年份未能成功招募到海床，因此缺少一个或多个年组，给人一种寿命较短的错误印象。对于这样一个小型物种来说，相对较长的寿命和浮游营养幼虫的发育是显着的，该地区的最大测试长度达到了 7.3 毫米，这些特征在大型底栖动物中更为典型。摄食方式类似于许多小型底栖动物类群的摄食方式。测试的架构赋予了卓越的强度和对机械扰动的弹性。