A larval revelation

摘要

The stalked crinoids, or sea lilies, are generally accepted as the most ancient of living echinoderms, with a fossil record extending back some 500 million years, almost to the base of the Palaeozoic. They live in deep water, and are difficult to collect in good enough condition for laboratory study. In consequence, their embryos and larvae have never been observed―until now, that is. On page 158 of this issue, Nakano et al. describe how they took advantage of the local crinoid populations in two deep bays, southwest of Tokyo, where adult animals come to within 100 m of the surface. Using gill nets rather than dredges and trawls, and enlisting the help of local fishermen, the authors obtained healthy, gravid individuals that spawned in the lab and produced viable embryos and larvae.