| 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. [1] Just like other ctenophores, over 95% of its body mass and composition is water. [2]
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; 9.9×10−5 to 0.048184 ounces). [2]
Callianira antarctica has been found in the waters of Southern Chile and Argentina, specifically the Strait of Magellan and Beagle Channel. [3] It has also been studied and observed in Antarctic waters in the Croker Passage [4] and Marguerite Bay. [5] It resides in water depths ranging from 30 to 400 m (98 to 1,312 ft), [6] 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. [7]
Callianira antarctica is carnivorous, and primarily hunts copepods, but during winter months will eat pteropods, and larval / juvenile krill. [8] Observed specimens gut contents show that they feed on species such as Calanoides acutus, Limacina helicina, [1] 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. [9] 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. [10] 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, [11] but some have been seen attached to the ice while hunting, and instead would hang their tentacles straight down to catch prey. [12]
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. [2]
Antarctic krill is a species of krill found in the Antarctic waters of the Southern Ocean. It is a small, swimming crustacean that lives in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic metre. It feeds directly on minute phytoplankton, thereby using the primary production energy that the phytoplankton originally derived from the sun in order to sustain their pelagic life cycle. It grows to a length of 6 centimetres (2.4 in), weighs up to 2 grams (0.071 oz), and can live for up to six years. It is a key species in the Antarctic ecosystem and in terms of biomass, is one of the most abundant animal species on the planet – approximately 500 million metric tons.
Ctenophora comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming, and they are the largest animals to swim with the help of cilia.
Krill are small and exclusively marine crustaceans of the order Euphausiacea, found in all the world's oceans. The name "krill" comes from the Norwegian word krill, meaning "small fry of fish", which is also often attributed to species of fish.
The crabeater seal, also known as the krill-eater seal, is a true seal with a circumpolar distribution around the coast of Antarctica. They are medium- to large-sized, relatively slender and pale-colored, found primarily on the free-floating pack ice that extends seasonally out from the Antarctic coast, which they use as a platform for resting, mating, social aggregation and accessing their prey. They are by far the most abundant seal species in the world. While population estimates are uncertain, there are at least 7 million and possibly as many as 75 million individuals. This success of this species is due to its specialized predation on the abundant Antarctic krill of the Southern Ocean, for which it has uniquely adapted, sieve-like tooth structure. Indeed, its scientific name, translated as "lobe-toothed (lobodon) crab eater (carcinophaga)", refers specifically to the finely lobed teeth adapted to filtering their small crustacean prey. Despite its common name, crabeater seals do not eat crabs. As well as being an important krill predator, the crabeater seal's pups are an important component of the diet of leopard seals. They are the only member of the genus Lobodon.
Thysanoessa is a genus of the krill that play critical roles in the marine food web. They're abundant in Arctic and Antarctic areas, feeding on zooplankton and detritus to obtain energy. Thysanoessa are responsible for the transportation of carbon and nutrients from surface waters to deeper trophic levels. This genus serves as prey for various fish and provide energy to marine ecosystems as they are at a low trophic level. Most travel through vertical migration, meaning they travel up and down in the water column, providing food for predators at the surface during the night, and at deeper levels during the day.
Diel vertical migration (DVM), also known as diurnal vertical migration, is a pattern of movement used by some organisms, such as copepods, living in the ocean and in lakes. The word "diel" comes from Latin: diēs, lit. 'day', and means a 24-hour period. The migration occurs when organisms move up to the uppermost layer of the sea at night and return to the bottom of the daylight zone of the oceans or to the dense, bottom layer of lakes during the day. It is important to the functioning of deep-sea food webs and the biologically driven sequestration of carbon.
Moroteuthopsis longimana, also known as the giant warty squid or longarm octopus squid, is a large species of hooked squid. It attains a mantle length of at least 85 cm and probably over 1.15 m. The largest complete specimen of this species, measuring 2.3 m in total length, was found in Antarctica in 2000.
Euphausia crystallorophias is a species of krill, sometimes called ice krill, crystal krill, or Antarctic coastal krill. It lives in the coastal waters around Antarctica, further south than any other species of krill. The specimens for the species' original description were collected through holes cut in the ice by Robert Falcon Scott's Discovery Expedition, several thousand having been donated by Thomas Vere Hodgson.
Syringammina is a xenophyophore found off the coast of Scotland, near Rockall. It is one of the largest single-celled organisms known, at up to 20 centimetres (8 in) across. It was first described in 1882 by the oceanographer John Murray, after being discovered on an expedition in the ship Triton which dredged the deep ocean bed off the west coast of Scotland in an effort to find organisms new to science. It was the first xenophyophore to be described and at first its relationship with other organisms was a mystery, but it is now considered to be a member of the Foraminifera.
Mertensia ovum, also known as the Arctic comb jelly or sea nut, is a cydippid comb jelly or ctenophore first described as Beroe ovum by Johan Christian Fabricius in 1780. It is the only species in the genus Mertensia. Unusually among ctenophores, which normally prefer warmer waters, it is found in the Arctic and adjacent polar seas, mostly in surface waters down to 50 metres (160 ft).
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and in the past billion years; basking sharks and copepods are just two examples of giant and microscopic organisms that feed upon plankton. Planktivory can be an important mechanism of top-down control that contributes to trophic cascades in aquatic and marine systems. There is a tremendous diversity of feeding strategies and behaviors that planktivores utilize to capture prey. Some planktivores utilize tides and currents to migrate between estuaries and coastal waters; other aquatic planktivores reside in lakes or reservoirs where diverse assemblages of plankton are present, or migrate vertically in the water column searching for prey. Planktivore populations can impact the abundance and community composition of planktonic species through their predation pressure, and planktivore migrations facilitate nutrient transport between benthic and pelagic habitats.
Circumpolar Deep Water (CDW) is a designation given to the water mass in the Pacific and Indian oceans that is a mixing of other water masses in the region. It is characteristically warmer and saltier than the surrounding water masses, causing CDW to contribute to the melting of ice shelves in the Antarctic region.
Bettina Meyer is a German Antarctic researcher, best known for her work on the ecology and physiology of invertebrates in the pelagic zone. She is the head of the ecophysiology of pelagic key species working group at the Alfred Wegener Institute for Polar and Marine Research (AWI).
Cindy Lee is a retired Distinguished Professor known for her research characterizing the compounds that comprise marine organic matter.
Phyllis Jean Stabeno is a physical oceanographer known for her research on the movement of water in polar regions. She has led award-winning research projects in the Arctic and was noted for a distinguished scientific career by the National Oceanic and Atmospheric Administration.
A micronekton is a group of organisms of 2 to 20 cm in size which are able to swim independently of ocean currents. The word 'nekton' is derived from the Greek νήκτον, translit. nekton, meaning "to swim", and was coined by Ernst Haeckel in 1890.
Carin Jessica Ashjian is an American biological oceanographer who is an associate scientist at the Woods Hole Oceanographic Institution. She studies how the physical environment influences the distribution of plankton in the Beaufort Sea.
Kendra Lee Daly is an oceanographer known for her work on zooplankton, particularly in low oxygen regions of the ocean. She is a professor at the University of South Florida, and an elected fellow of the American Association for the Advancement of Science.
Iliana B. Baums is a professor at Pennsylvania State University known for her work on coral reef ecology.
Stephanie Louise Pfirman is a professor at Arizona State University known for her work on sea ice, pollutants in sea ice, and how sea ice is changing over time. She is a fellow of the American Association for the Advancement of Science.
{{cite book}}: CS1 maint: date and year (link)