Xenoturbella profunda

Xenoturbella profunda, the purple sock or sock worm,[2] is a marine, benthic, deep-water worm-like species that belongs to the genus Xenoturbella. It was discovered in eastern Pacific Ocean by a group of Californian and Australian scientists.[3][4][5] The species was described in 2016 from seven specimens.[1]

Xenoturbella profunda
A congeneric species of X. profunda (X. japonica).
Scientific classification
Kingdom: Animalia
Phylum: Xenacoelomorpha
Family: Xenoturbellidae
Genus: Xenoturbella
Species:
X. profunda
Binomial name
Xenoturbella profunda
Rouse, Wilson, Carvajal & Vrijenhoek, 2016[1]
Longitudinal section of a congeneric species, Xenoturbella bocki

X. profunda shares morphological similarities with other species of the genus Xenoturbella, and is known for lacking respiratory, circulatory and an excretory system.[6]

Description

The etymology of the species name refers to the fact that it lives deepest of the known xenoturbellids.[7]

Xenoturbella profunda individuals were sampled at ca. 3,700 m depth near a carbonate-hosted hydrothermal vent in the Gulf of California.[8] This animal is 15 cm (5.9 in) in length, with a uniform pale pink colouration. The body wall displays several furrows: on the circumference, on the side, and two deep, longitudinal, dorsal ones. The longitudinal orientation involves a rounded anterior end, while the posterior end gradually reduces in thickness. The mouth is orientated ventrally, anterior to the ring furrow. The live specimens exhibited an epidermal ventral glandular network branching over two-thirds of the ventral surface. The species is gonochoric, and gametes are present dorsally and ventrally in the body wall.[1] Tissues contain exogenous DNA corresponding to a bivalve mollusk, the vesicomyid Archivesica gigas.[1]

Phylogeny

Comparison of mitochondrial DNA and protein sequences showed that the species X. profunda is the sister group to X. churro. In turn, these two species share evolutionary affinities with X. monstrosa into a clade of 'deep-water' taxa.

Species-level cladogram of the genus Xenoturbella.
  Xenacoelomorpha  
  Xenoturbella  
  'Shallow' clade  
         

  X. japonica

 
 
         

  X. bocki

 
 

  X. hollandorum

 
 
 
  'Deep' clade  
         

  X. monstrosa

 
 
         

  X. churro

 
 

  X. profunda

 
 
 
 
 

  Acoelomorpha  

 
 
The cladogram has been reconstructed from mitochondrial DNA and protein sequences.[1][9]

References
  1. Rouse, Greg W.; Wilson, Nerida G.; Carvajal, Jose I.; Vrijenhoek, Robert C. (2016-02-04). "New deep-sea species of Xenoturbella and the position of Xenacoelomorpha". Nature. 530 (7588): 94–97. doi:10.1038/nature16545. ISSN 0028-0836.
  2. "The deep sea: Where poisons become nutrients". Deutsche Welle (www.dw.com). Retrieved 2020-03-11.
  3. Khan, Amina (2016-02-05). "Newly discovered deep-sea worms, including one named 'churro,' could shed light on animal evolution". Los Angeles Times. Retrieved 2020-03-10.
  4. Morelle, Rebecca (2016-02-03). "Mystery of 'sock of the deep' solved". BBC News. Retrieved 2020-03-10.
  5. "We finally know what to make of these 'purple sock' creatures that litter the sea floor". ZME Science. 2016-02-05. Retrieved 2020-03-11.
  6. Nakano, Hiroaki (2015). "What is Xenoturbella?". Zoological Letters. 1 (22): 22. doi:10.1186/s40851-015-0018-z. PMC 4657256. PMID 26605067.
  7. "Around the Pier: Churro-Like Marine Worm Discovered by Scripps Scientists Is One of the 'Top 10 Species of 2017'". Scripps Institution of Oceanography. 2017-05-30. Retrieved 2020-03-10.
  8. Goffredi, Shana K.; Johnson, Shannon; Tunnicliffe, Verena; Caress, David; Clague, David; Escobar, Elva; Lundsten, Lonny; Paduan, Jennifer B.; Rouse, Greg; Salcedo, Diana L.; Soto, Luis A. (2017-07-26). "Hydrothermal vent fields discovered in the southern Gulf of California clarify role of habitat in augmenting regional diversity". Proceedings of the Royal Society B: Biological Sciences. 284 (1859): 20170817. doi:10.1098/rspb.2017.0817. PMC 5543219. PMID 28724734.
  9. Nakano, Hiroaki; Miyazawa, Hideyuki; Maeno, Akiteru; Shiroishi, Toshihiko; Kakui, Keiichi; Koyanagi, Ryo; Kanda, Miyuki; Satoh, Noriyuki; Omori, Akihito; Kohtsuka, Hisanori (2017-12-18). "A new species of Xenoturbella from the western Pacific Ocean and the evolution of Xenoturbella". BMC Evolutionary Biology. 17 (1): 245. doi:10.1186/s12862-017-1080-2. ISSN 1471-2148. PMC 5733810. PMID 29249199.


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