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PUBLIC RELEASE DATE:
19-May-2008

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Contact: Charlotte Webber
charlotte.webber@biomedcentral.com
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BioMed Central
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Clue to mystery crustacean in parasite form

IMAGE: Y larvae.

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First identified in 1899, y-larvae have been one of the greatest zoological mysteries for over a century. No one has ever found an adult of these puzzling crustaceans, despite the plethora of these larvae in plankton, leading generations of marine zoologists to wonder just what y- larvae grow up to be. A study published in BioMed Central's open access journal, BMC Biology, reports the transformation of the larvae into a previously unseen, wholly un-crustacean-like, parasitic form.

Y larvae, or facetotectans, are found amongst marine plankton in oceans from the poles to the tropics. In coral reef areas they occur dizzying diversity, even though they are ubiquitous and similar to the larvae of barnacles, not one adult y-organism has been identified in over 100 years of considerable searching.

"Facetotectans are the only crustacean group with a taxonomy based solely on larval stages", say Henrik Glenner and Jens Hoeg (University of Copenhagen) and colleagues from Japan "but the great species diversity indicates that the adults play an important ecological role." Supported by the Carlsberg Foundation in Denmark and the Lake Biwa Museum in Japan, the study authors collected the study authors collected over 40 species of y larvae from one site at Sesoko Island near Okinawa, Japan, and exposed many of them to a crustacean moulting-hormone to encourage them to mature. The free-swimming y-larvae shed their articulated exoskeleton, and a simple, slug- like, pulsing mass of cells emerged.

The authors explain "The musculature and compound eyes that you might expect to see in adult crustaceans were in a state of degeneration, and from our observations of the live, and also preserved specimens, we conclude that the adults of these larvae must be parasites - but of what we do not know."

The closest relatives of the facetotectans among the crustaceans are barnacles and another group, the Ascothoracida, both of which have similar larval stages and both of which have parasitic representatives. The stage induced in this study - the so called ypsigons - are not adults but another juvenile, post y-larva stage; the similarity between them and juveniles of the highly specialised parasitic rhizocephalan barnacles is, according to Glenner and colleagues, a remarkable example of convergent evolution.

The great diversity of Facetotecta and the finding that they are most likely parasitic as adults hints at a major ecological role that future studies, both in laboratories and in the field will try to uncover. These finding provide a tantalising glimpse of the solution to this 100-year-old riddle.

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Notes to Editors

1. Induced metamorphosis in crustacean y-larvae: Towards a solution to a 100-year-old riddle
Henrik Glenner, Jens T Hoeg, Mark J Grygier and Yoshihisa Fujita
BMC Biology (in press)

During embargo, article available here: http://www.biomedcentral.com/imedia/1526981237193565_article.pdf?random=340898

After the embargo, article available at the journal website: http://www.biomedcentral.com/bmcbiol/

Please name the journal in any story you write. If you are writing for the web, please link to the article. All articles are available free of charge, according to BioMed Central's open access policy.

Article citation and URL available on request at press@biomedcentral.com on the day of publication

2. BMC Biology - the flagship biology journal of the BMC series - publishes open access research and methodology articles of special importance and broad interest in any area of biology and biomedical sciences. BMC Biology (ISSN 1741-7007) is covered by PubMed, MEDLINE, BIOSIS, CAS, Scopus, EMBASE, Zoological Record, Thomson Scientific (ISI) and Google Scholar. The journal will receive its first Impact Factor in 2008.

3. BioMed Central (www.biomedcentral.com) is an independent online publishing house committed to providing immediate access without charge to the peer-reviewed biological and medical research it publishes. This commitment is based on the view that open access to research is essential to the rapid and efficient communication of science.



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