Thetys (tunicate)
Thetys vagina, or the twin sailed salp, is the largest known solitary species of salp and the only valid species of the genus Thetys. First described by W.G Tilesius in 1802, the species is transparent and gelatinous, making it difficult to be seen in water, which is helpful in avoiding predators.[1][2][3] The fossil range is very recent.[4] Other animals often mistaken for T. vagina are Salpa fusiformis, Aurelia aurita, and Pegea confoederata. There is no known status of conservation in this species. T. vagina DNA was sequenced as part of a larger project in 2014 where spiny lobster larvae were found attached to T. vagina and consuming it.[5]
| Thetys | |
|---|---|
| Thetys vagina (Salpa vagina) | |
| Scientific classification | |
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| Genus: | Thetys Tilesius, 1802 |
| Species: | T. vagina |
| Binomial name | |
| Thetys vagina Tilesius, 1802 | |
| Synonyms | |
| Thetys costata (Quoy & Gaimard, 1825) | |
Description edit
T. vagina can reach up to 333 mm (13 in) long.[6] They develop into two distinct forms; the aggregate generation and the solitary generation. The aggregated sexual blastozooids (aggregate form) can get to the size of 250 mm and has five muscle bands. The solitary asexual oozooids (solitary form) can get to size of 300 mm.[7] Vaginas of this form have around 20 muscle bands, which are characterized as “striped” with two short dark-colored tentacles at their ends, attached at the upper and lower halves of the body.[8] Both the aggregate and the solitary forms have tests covered in ridges and grooves. They have a colored digestive system seen as a dark or colorful lump.[8] The embryos have been found to be between 10-15 mm.[9]
Distribution edit
T. vagina is found in pelagic marine environments.[10] It occurs in tropical and temperate waters of the Pacific, Atlantic and Indian Ocean and is occasionally found in colder waters in the northern Atlantic, likely following warm water currents.[9][6][7] The species is widespread but at low density (although they may occasionally be found at very high density), resulting in only rare accounts of it being caught.[7]
T. vagina has been found off the central coast of British Columbia, marking its north-most occurrence to date.[3] It has been found by cataloging volunteers along the West Coast of the U.S. and reportedly congests nets of fisherman off the coast of northern Honshu and southern Hokkaido, Japan.[7] In January 2009, the largest measured biomass of T. vagina was recorded at 852 g WW m−3 in the Tasman sea.[11]
T. vagina stays in the photic zone and is often found in places of high chlorophyll concentration, likely due to its phytoplankton rich diet.[7] A large increase of T. vagina is associated with an increase in phytoplankton.[7] The ecology of this species is not fully understood.[7]
Diet edit
Like other salps, T. vagina feeds by consuming plankton nutrient water on one end of its body, filtering it via an internal net made of mucus, and spewing the water out the other end.[3] Their internal net is very effective, catching particles spanning four magnitudes in size.[8] This action also allows them to move through the water column, classifying them as nektonic. T. vagina feeds on marine plankton, including single-celled organisms such as dinoflagellates, silicoflagellates, diatoms, and tintinnids, as well as copepods and other small particles.[7] Continuing up the food chain, T. vagina is preyed upon by medusae, siphonophores, ctenophores, heteropods, sea turtles, late stage larvae of the spiny lobster, marine birds, along with various species of fish.[7] They have a high energy content at (11.00 kJ g−1 DW).[11]
In a study done in the Japan Sea in 2006, the gut contents of T. vagina where evaluated.[7] The diatom Coscinodiscus spp. (13–55 µm in diameter) was found to be the major makeup of the guts, with the diatom Coscinodiscus wailesii (219–313 µm) being the second most prevalent.[7] Another study off the coast of Maine found T. vagina gut content to be mainly made up of two dinoflagellates; Prorocentrummicans and Dinophysis norvegica. The study also found T. vagina to be an indiscriminate feeder over a broad size spectrum.[9]
Ecology edit
Waste from T. vagina is densely packed, sinks quickly, and is full of carbon. Their carcasses also sink quickly and are carbon rich (31% dry weight, DW).[11] This makes them efficient carbon sinks, but also harder to study. This carbon exchange could be responsible for up to 67% of the mean organic daily carbon flux in the area.[11] In 2007 and 2009, the Tasman sea floor was analyzed from 200m to 2500m in depth and large quantities of T. vagina were found. The quantities found were some of the largest gelatinous zooplankton depositions ever recorded.[11] Further, benthic communities were found consuming T. vagina carcasses.[11] This sink provides nutrients to these benthic communities and are likely a large source of carbon input.[11]
Etymology edit
The generic name of Thetys refers to Tethys or Thetis, Greek mythological figures.[12][13] The former being the mother of river gods and the Oceanids, and the latter being the goddess of water, a nereid, or a sea nymph. The species epithet is Latin vagina and means "sheath" or "scabbard."[13][12] At the time of Tilesius' naming, the term had not acquired the modern-day anatomical meaning and had referred solely to a sheath, likely referring to its appearance.[12]
References edit
- ^ "Zweiunddreißigster Abschnitt von der Ostküste Südamerikas nach Südafrika oder dem Indischen Ozean" [Thirty-second section from the east coast of South America to South Africa or the Indian Ocean]. Segelhandbuch für den Atlantischen Ozean (in German). 1910. pp. 554–556. doi:10.1515/9783111587325-033. ISBN 978-3-11-158732-5.
- ^ Karnauskas, Kristopher B.; Witting, Jan H. (17 July 2014). "Shipboard ADCP profiles, central equatorial Pacific Ocean, 2003-2012". doi:10.1575/1912/6746. hdl:1912/6835.
{{cite journal}}: Cite journal requires|journal=(help) - ^ a b c "D. Wrobel, C. Mills Pacific coast pelagic invertebrates. A guide to the common gelatinous animals. 108 p. Sea Challengers and Monterey Bay Aquarium, 1998. Price". Journal of the Marine Biological Association of the United Kingdom. 78 (4): 1392. November 1998. doi:10.1017/S0025315400044660.
- ^ "Tetys". World Register of Marine Species.
- ^ O'Rorke, Richard; Lavery, Shane D.; Wang, Miao; Gallego, Ramón; Waite, Anya M.; Beckley, Lynnath E.; Thompson, Peter A.; Jeffs, Andrew G. (1 July 2015). "Phyllosomata associated with large gelatinous zooplankton: hitching rides and stealing bites". ICES Journal of Marine Science. 72: i124–i127. CiteSeerX 10.1.1.982.4632. doi:10.1093/icesjms/fsu163.
- ^ a b Sims, David W. (August 1996). "A Rare Record of the Salp, Thetys Vagina (Tunicata: Thaliacea) From Western Scottish Waters". Journal of the Marine Biological Association of the United Kingdom. 76 (3): 833–834. doi:10.1017/s0025315400031519. S2CID 85601425.
- ^ a b c d e f g h i j k Iguchi, N. (2006). "Horizontal distribution of Thetys vagina Tilesius (Tunicata, Thaliacea) in the Japan Sea during spring 2004". Journal of Plankton Research. 28 (6): 537–541. doi:10.1093/plankt/fbi138.
- ^ a b c Yount, James L. (July 1954). "The Taxonomy of the Salpidae (Tunicata) of the Central Pacific Ocean". hdl:10125/9190.
{{cite journal}}: Cite journal requires|journal=(help) - ^ a b c McAlice, B. J. (1 November 1986). "Occurrence of Thetys vagina Tilesius (Tunicata, Thaliacea) on the coast of Maine". Bulletin of Marine Science. 39 (3): 717–718.
- ^ Miller, Rebecca; Santora, Jarrod; Auth, Toby; Sakuma, Keith; Wells, Brian; Field, John; Brodeur, Richard (2019). "Distribution of pelagic thaliaceans, Thetys vagina and Pyrosoma atlanticum, during a period of mass occurrence within the California Current" (PDF). California Cooperative Oceanic Fisheries Investigations Report. 60: 94–108.
- ^ a b c d e f g Henschke, Natasha; Everett, Jason D.; Suthers, Iain M. (December 2016). "An observation of two oceanic salp swarms in the Tasman Sea: Thetys vagina and Cyclosalpa affinis". Marine Biodiversity Records. 9 (1): 21. doi:10.1186/s41200-016-0023-8. S2CID 49236952.
- ^ a b c Heyden, Dylan (18 November 2016). "The Thetys Vagina Might Be the Strangest Name for A Sea Creature Ever". The Inertia. Retrieved 1 November 2021.
- ^ a b Fretwell, Kelly (2018). "Twin-sailed salp • Thetys vagina". Biodiversity of the Central Coast. Retrieved 1 November 2021.
External links edit
- Photograph
- Video of swimming behavior on YouTube