Document Detail


Larval stages of a living sea lily (stalked crinoid echinoderm).
MedLine Citation:
PMID:  12520300     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The embryos and larvae of stalked crinoids, which are considered the most basal group of extant echinoderms, have not previously been described. In contrast, much is known about the development of the more accessible stalkless crinoids (feather stars), which are phylogenetically derived from stalked forms. Here we describe the development of a sea lily from fertilization to larval settlement. There are two successive larval stages: the first is a non-feeding auricularia stage with partly longitudinal ciliary bands (similar to the auricularia and bipinnaria larvae of holothurian and asteroid echinoderms, respectively); the second is a doliolaria larva with circumferential ciliary bands (similar to the earliest larval stage of stalkless crinoids). We suggest that a dipleurula-type larva is primitive for echinoderms and is the starting point for the evolution of additional larval forms within the phylum. From a wider evolutionary viewpoint, the demonstration that the most basal kind of echinoderm larva is a dipleurula is consistent with Garstang's auricularia theory for the phylogenetic origin of the chordate neural tube.
Authors:
Hiroaki Nakano; Taku Hibino; Tatsuo Oji; Yuko Hara; Shonan Amemiya
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Nature     Volume:  421     ISSN:  0028-0836     ISO Abbreviation:  Nature     Publication Date:  2003 Jan 
Date Detail:
Created Date:  2003-01-09     Completed Date:  2003-02-12     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0410462     Medline TA:  Nature     Country:  England    
Other Details:
Languages:  eng     Pagination:  158-60     Citation Subset:  IM    
Affiliation:
Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bldg. FSB-501, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan.
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MeSH Terms
Descriptor/Qualifier:
Animals
Echinodermata / anatomy & histology,  growth & development*
Evolution
Female
Fertilization
Larva / anatomy & histology,  growth & development*
Male
Phylogeny
Comments/Corrections
Comment In:
Nature. 2003 Jan 9;421(6919):120-1   [PMID:  12520284 ]

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