Xenoturbella is a genus of bilaterian animals; it contains two marine worm-like species. The first known species was discovered in 1915 but was only described in 1949. A 2003 DNA study has shown it is a primitive deuterostome phylum. The genus was the first member of its subphylum (the Xenoturbellida) to be discovered.
This phylum is basal within the deuterostomes. It is related to the Acoelomorpha, forming a sister clade to the echinoderms and hemichordates. Other members of this phylum are now known.
Xenoturbella has a very simple body plan: it has no brain, no through gut, no excretory system, no organized gonads (but does have gametes), or any other organs except for a statocyst containing flagellated cells. It has cilia and a diffuse nervous system. The animal is up to 4 centimetres (1.6 in) long, and has been found off the coasts of Sweden, Scotland and Iceland.
The association of specimens of Xenoturbella with mollusc larva has led many to suggest that they are molluscivores. However, another idea is that the Xenoturbella larval stage develops as an internal parasite of certain molluscs.
The genus Xenoturbella contains two species:
- Xenoturbella bocki
- Xenoturbella westbladi
References[change | change source]
- ↑ Zhang, Zhi-Qiang (2011-12-23). "Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness". Zootaxa. Magnolia Press. 3148: 1–237. doi:10.11646/zootaxa.3148.1.1. Retrieved 2016-02-03.
- ↑ Tyler, S.; Schilling, S.; Hooge, M.; Bush, L.F. (2006–2016). "Xenoturbella". Turbellarian taxonomic database. Version 1.7. Archived from the original on 2019-02-09. Retrieved 2016-02-03.
- ↑ Westblad 1949. Arkiv. Zoologi. 1:3-29
- ↑ Bourlat S.J. et al. 2003. Xenoturbella is a deuterostome that eats molluscs. Nature 424 (6951): 925–928 
- ↑ G. Haszprunar R.M. & Rieger P. Schuchert 1991. "Extant 'problematica' within or near the Metazoa." In: Simonetta A.M. & Conway Morris S. (eds): The early evolution of metazoa and the significance of problematic taxa. Oxford Univ. Press. 99–105
- ↑ Bourlat S.J. et al. 2006. Deuterostome phylogeny reveals monophyletic chordates and the new phylum Xenoturbellida. Nature 444 (7115): 85–88 
- ↑ Perseke M. et al 2007. The mitochondrial DNA of Xenoturbella bocki: genomic architecture and phylogenetic analysis. Theory Biosci. 126(1):35-42. Available on-line at 
- ↑ Philippe H. et al. 2011. Acoelomorph flatworms are deuterostomes related to Xenoturbella. Nature 470 (7333): 255-258 
- ↑ Morrelle, Rebecca 2016. Mystery of the deep-sea 'purple sock' solved. 
- ↑ Enigmatic worm identified as mankind's long lost relative Archived 2010-10-09 at the Wayback Machine – Accessed January 3, 2008
- ↑ Xenoturbella – Back to the basics Archived 2007-12-10 at the Wayback Machine – Accessed January 3, 2008