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Callianira antarctica
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Ctenophora
Class:	Tentaculata
Order:	Cydippida
Family:	Mertensiidae
Genus:	Callianira
Species:	C. antarctica
Binomial name
Callianira antarctica Chun, 1897

Callianira antarctica is a species of ctenophore that physically resembles Mertensia ovum, but lacks the oil sacs. Just like other ctenophores, over 95% of its body mass and composition is water.

Physical description

Callianira antarctica studied in 2002 ranged in size from 35 to 83.6 mm (1.38 to 3.29 in) in autumn months, and from 8.5 to 98 mm (0.33 to 3.86 in) in winter months. Their weight ranged from 150 to 758 mg (2.31 to 11.70 grains; 0.0053 to 0.0267 ounces) in autumn, and in winter they ranged from 2.8 to 1,366 mg (0.043 to 21.081 grains; 9.9×10 to 0.048184 ounces).

Distribution

Callianira antarctica has been found in the waters of Southern Chile and Argentina, specifically the Strait of Magellan and Beagle Channel. It has also been studied and observed in Antarctic waters in the Croker Passage and Marguerite Bay. It resides in water depths ranging from 30 to 400 m (98 to 1,312 ft), but through sampling it was seen that the highest abundance of ctenophores was found to be between 120–150 m (390–490 ft) during the day, and about 250 m (820 ft) at night.

Ecology

Callianira antarctica is carnivorous, and primarily hunts copepods, but during winter months will eat pteropods, and larval / juvenile krill. Observed specimens gut contents show that they feed on species such as Calanoides acutus, Limacina helicina, Calanus propinquus, metridia gerlachi, and larval/juvenile Euphausia superba. C. antarctica was observed to have a seasonal feeding on krill larvae that takes place underneath the sea ice. C. antarctica hunts by swimming in a circle pattern under the ice with its tentacles outstretched. C. antarctica's tentacles use colloblasts which stick prey to the tentacles. Then C. antarctica would retract the tentacle into its mouth and down to its gut where digestion would occur. Typically C. antarctica would hunt underneath the sea ice and swim horizontally, but some have been seen attached to the ice while hunting, and instead would hang their tentacles straight down to catch prey.

Digestion in observed specimens took anywhere from 5 hours to 46 hours. Callianira antarctica was seen excreting the hard exoskeletons of its prey after digesting the soft insides. C. antarctica needs carbon and lipids from its prey to survive, and it is thought that these needs increase during the winter months, and when in the juvenile stage of life. Unlike Mertensia ovum, Callianira antarctica has no oil sacs, and instead stores lipids in the stomodeum. Body carbon is distributed among tentacles, the gut wall, and comb rows.

References

1. ^ Larson, R. J.; Harbison, G. R. (1989). "Source and Fate of Lipids in Polar Gelatinous Zooplankton". Arctic. 42 (4): 339–346. ISSN 0004-0843.
2. ^ Scolardi, Kerri M.; Daly, Kendra L.; Pakhomov, Evgeny A.; Torres, Joseph J. (2006-07-18). "Feeding ecology and metabolism of the Antarctic cydippid ctenophore Callianira antarctica". Marine Ecology Progress Series. 317: 111–126. doi:10.3354/meps317111. ISSN 0171-8630.
3. Pagès, Francesc; Orejas, Covadonga (1999-12-30). "Medusae, siphonophores and ctenophores of the Magellan Region". Scientia Marina. 63 (S1): 51–57. doi:10.3989/scimar.1999.63s151. hdl:10261/5262. ISSN 1886-8134.
4. Lancraft, Thomas M.; Reisenbichler, Kim R.; Robison, Bruce H.; Hopkins, Thomas L.; Torres, Joseph J. (2004-08-01). "A krill-dominated micronekton and macrozooplankton community in Croker Passage, Antarctica with an estimate of fish predation". Deep Sea Research Part II: Topical Studies in Oceanography. Integrated Ecosystem Studies of Western Antarctic Peninsula Continental Shelf Waters and Related Southern Ocean Regions. 51 (17): 2247–2260. doi:10.1016/j.dsr2.2004.07.004. ISSN 0967-0645.
5. Hofmann, Eileen; Klinck, John; Costa, Dan; Daly, Kendra; Torres, Joseph; Fraser, William (2002-01-01). "U.S. Southern Ocean Global Ecosystems Dynamics Program". Oceanography. 15 (2): 64–74. doi:10.5670/oceanog.2002.22.
6. Schiariti, Agustín; Sofía Dutto, Maria; Oliveira, Otto M.; Faillia Siquier, Gabriela; Puente Tapia, Francisco Alejandro; Chiaverano, Luciano (2020-06-25). "Overview of the comb jellies (Ctenophora) from the South-western Atlantic and Sub Antarctic region (32–60°S; 34–70°W)". New Zealand Journal of Marine and Freshwater Research: 1–25. doi:10.1080/00288330.2020.1775660. ISSN 0028-8330.
7. Scolardi, Kerri (2004-03-25). "Distribution, Metabolism and Trophic Ecology of the Antarctic Cydippid Ctenophore, Callianira antarctica, West of the Antarctic Peninsula". USF Tampa Graduate Theses and Dissertations.
8. Ju, Se-Jong; Scolardi, K.; Daly, K. L.; Harvey, H. Rodger (2004-11-01). "Understanding the trophic role of the Antarctic ctenophore, Callianira antarctica, using lipid biomarkers". Polar Biology. 27 (12): 782–792. doi:10.1007/s00300-004-0652-y. ISSN 1432-2056.
9. Flores, Hauke; van Franeker, Jan-Andries; Cisewski, Boris; Leach, Harry; Van de Putte, Anton P.; Meesters, Erik (H. W. G. ); Bathmann, Ulrich; Wolff, Wim J. (2011-10-01). "Macrofauna under sea ice and in the open surface layer of the Lazarev Sea, Southern Ocean". Deep Sea Research Part II: Topical Studies in Oceanography. Southern Ocean Biodiversity — From Pelagic Processes to Deep-Sea Response. 58 (19): 1948–1961. doi:10.1016/j.dsr2.2011.01.010. ISSN 0967-0645.
10. Madin, Lawrence P.; Hamner, William M.; Haddock, Steven H. D.; Matsumoto, George I. (2013). "Scuba diving in blue water: a window on ecology and evolution in the epipelagic ocean.". Research and Discoveries: The Revolution of Science Through Scuba. Smithsonian Contributions to the Marine Sciences, 39. Smithsonian Institution Scholarly Press.{{cite book}}: CS1 maint: date and year (link)
11. Hamner, W. M.; Hamner, P. P.; Obst, B. S.; Carleton, J. H. (1989). "Field observations on the ontogeny of schooling of Euphausia superba furciliae and its relationship to ice in Antarctic waters". Limnology and Oceanography. 34 (2): 451–456. doi:10.4319/lo.1989.34.2.0451.
12. Kiko, Rainer; Michels, Jan; Mizdalski, Elke; Schnack-Schiel, Sigrid B.; Werner, Iris (2008-04-01). "Living conditions, abundance and composition of the metazoan fauna in surface and sub-ice layers in pack ice of the western Weddell Sea during late spring". Deep Sea Research Part II: Topical Studies in Oceanography. Ice Station POLarstern (ISPOL): Results of interdisciplinary studies on a drifting ice floe in the western Weddell Sea. 55 (8): 1000–1014. doi:10.1016/j.dsr2.2007.12.012. ISSN 0967-0645.

• Tentaculata