Development Genes and Evolution

, Volume 215, Issue 7, pp 358–363 | Cite as

Eggs and embryos in Xenoturbella (phylum uncertain) are not ingested prey

  • Olle IsraelssonEmail author
  • Graham E. Budd
Original Article


Xenoturbella is an enigmatic animal that has puzzled science for almost a century. The eggs and embryos found in Xenoturbella have recently been interpreted as ingested prey. However, PCR on individual eggs as well as in situ hybridisation and in situ PCR unambiguously show that they are Xenoturbella’s own. The eggs and embryos are individually enclosed within follicles with the same ultrastructure. The cortical granules in oocytes and eggs from Xenoturbella but not Nucula stained positively with an antiserum against Reissner’s substance. The embryos incorporated 5-bromodeoxyuridine in vivo, i.e. they replicate their genome and are living.


Xenoturbella Deuterostome evolution Cytochrome oxidase 



We thank M. Thorndyke, T. Stach, S. Dupont (Kristineberg Marine Laboratory, Sweden), E. Danell, G. Engström, S. Gunnarsson, K. Johansson, H. Malmikumpu, G. Malsher, M. Mattsson (Uppsala University), D. Lindberg, K. McDonald, R. Zalpuri (University of California Berkeley) and M. Svensson (Friedrich-Schiller-Universität, Jena, Germany) for invaluable support. The rainbow trout ovaries were kindly donated by M. Jönsson (Uppsala University). Some X. westbladi were sequenced by G. Giribet (Harvard University).

Supplementary material

427_2005_485_ESM_supp.pdf (308 kb)
(308 KB)


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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  1. 1.Museum of EvolutionUppsala UniversityUppsalaSweden
  2. 2.Department of Earth Sciences, PaleobiologyUppsala UniversityUppsalaSweden

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