Xenoturbella monstrosa
Xenoturbella monstrosa, a deep-sea giant purple sock worm, 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.[2][3][4] The species was described in 2016 from several specimens.[1]
| Xenoturbella monstrosa | |
|---|---|
 | |
| A congeneric species of X. monstrosa (X. japonica) | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Xenacoelomorpha |
| Family: | Xenoturbellidae |
| Genus: | Xenoturbella |
| Species: | X. monstrosa |
| Binomial name | |
| Xenoturbella monstrosa Rouse, Wilson, Carvajal & Vrijenhoek, 2016[1] | |
Xenoturbella monstrosa shares morphological similarities with other species of the genus Xenoturbella, and is known for lacking respiratory, circulatory and an excretory system.[5]
Description
The etymology of the species name refers to its unusual large size among known xenoturbellids.[6]
Xenoturbella monstrosa is 20 cm (7.9 in) in length, with a purple or 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 in front of the ring furrow, while the posterior end gradually reduces in thickness. The mouth is orientated ventrally, halfway between the anterior end and the ring furrow. The live specimens exhibited an epidermal ventral glandular network branching over two-thirds of the ventral surface. Gametes are present dorsally and ventrally in the body wall.[1] Tissues contain exogenous DNA corresponding to bivalve mollusks, the vesicomyid Archivesica diagonalis and Calyptogena pacifica.[1]
Phylogeny
Comparison of mitochondrial DNA and protein sequences showed that the species X. monstrosa is the sister group to X. churro and X. profunda into a clade of 'deep-water' taxa.
| Species-level cladogram of the genus Xenoturbella. | |||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||
| The cladogram has been reconstructed from mitochondrial DNA and protein sequences.[1][7] |
References
- 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. PMID 26842060. S2CID 3870574.
- 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.
- Morelle, Rebecca (2016-02-03). "Mystery of 'sock of the deep' solved". BBC News. Retrieved 2020-03-10.
- "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.
- Nakano, Hiroaki (2015). "What is Xenoturbella?". Zoological Letters. 1 (22): 22. doi:10.1186/s40851-015-0018-z. PMC 4657256. PMID 26605067.
- "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.
- 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.