Muggiaea atlantica | |
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Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Cnidaria |
Class: | Hydrozoa |
Order: | Siphonophorae |
Family: | Diphyidae |
Genus: | Muggiaea |
Species: | M. atlantica |
Binomial name | |
Muggiaea atlantica Cunningham, 1892 [1] | |
Muggiaea atlantica is a species of small hydrozoan, a siphonophore in the family Diphyidae. It is a cosmopolitan species occurring in inshore waters of many of the world's oceans, and it has colonised new areas such as the North Sea and the Adriatic Sea. It is subject to large population swings, and has been held responsible for the death of farmed salmon in Norway. The species was first described by J.T. Cunningham in 1892 from a specimen obtained at Plymouth, England.
Muggiaea atlantica is a small colonial siphonophore, but one of the two nectophores (swimming bells) is undeveloped. The remaining nectophore grows to a length of about 7 mm (0.3 in). It is translucent and has five straight, longitudinal ridges, some of which may form a keel. The hydroecium (ventral cavity) is about one third of the length of the nectophore, and the long slender somatocyst (extension of the gastrovascular system) reaches the apex of the nectosac (central cavity) and sometimes contains oil droplets. [2] [3] The eudoxid (reproductive stage) soon becomes detached. It has a cone-shaped, asymmetric bract with a wide flanged suture running from apex to base. The right edge of the bract is curved while the left edge is truncated horizontally. The lower surface has a small cavity in which the somatocyst is situated. [4]
Muggiaea atlantica is a neritic species that forms part of the zooplankton, and is found in the upper hundred metres of inshore temperate and subtropical waters worldwide. It is present in the Atlantic Ocean, the Mediterranean Sea, the Pacific Ocean and the Indian Ocean. It is a common siphonophore and probably more abundant than any other species of siphonophore in nearshore habitats. Its abundance is seasonal, and in parts of the northern hemisphere it has population peaks in May/June and again in September/November. [5] In the western English Channel it occurred sporadically before the 1960s but after 1968 it became resident. Its seasonal distribution and abundance seem to be associated with sea temperature changes and the availability of food. [6] It appeared in the southern Adriatic Sea for the first time in the mid 1990s and became increasingly common there. It was detected in the marine lakes on the island of Mljet in southern Croatia in 2001, and seems to have displaced Muggiaea kochii in the Great Lake there. It is hypothesized that the cold winter of 2000/2001 favoured the more cold-tolerant M. atlantica over the warm-temperate M. kochii. [7]
Muggiaea atlantica swims in an arc, propelled by pulsations of its bell, and then remains stationary for several minutes. [8] It feeds almost entirely on copepods, consuming an estimated five to ten prey items daily, mostly during the night. [9] In the eastern Pacific it is eaten by predatory fish such as the blue rockfish (Sebastes mystinus), and by the floating sea snail Carinaria cristata . [5]
Reproduction in this species is by an alternation of generations between an asexual polygastric animal (bearing both asexual and reproductive elements) and the sexual eudoxid stage which becomes detached from the nectophore. The generation time is short and under favourable conditions, numbers can build up rapidly. [6]
A population explosion of M. atlantica in the North Sea in 1989 caused major changes in the composition of the community. The siphonophere was present at densities of five hundred per cubic metre and this depleted the copepods normally present. This resulted in a reduction in the grazing pressure on the phytoplankton and an increase in their growth, causing an algal bloom and other cascading ecosystem effects. [10]
The aquaculture industry in Norway suffered a setback in 2007 when more than 100,000 caged salmon were killed by a bloom of M. atlantica, present at a concentration of 2,000 per cubic metre in coastal waters. [8] This siphonophore is also thought to have been involved in the loss of a million farmed salmon in Ireland in 2003. [11]
Plankton are the diverse collection of organisms found in water that are unable to propel themselves against a current. The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish, and baleen whales.
Zooplankton are the animal component of the planktonic community. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequently, they drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers.
Siphonophorae is an order within Hydrozoa, which is a class of marine organisms within the phylum Cnidaria. According to the World Register of Marine Species, the order contains 175 species thus far.
Holoplankton are organisms that are planktic for their entire life cycle. Holoplankton can be contrasted with meroplankton, which are planktic organisms that spend part of their life cycle in the benthic zone. Examples of holoplankton include some diatoms, radiolarians, some dinoflagellates, foraminifera, amphipods, krill, copepods, and salps, as well as some gastropod mollusk species. Holoplankton dwell in the pelagic zone as opposed to the benthic zone. Holoplankton include both phytoplankton and zooplankton and vary in size. The most common plankton are protists.
Chrysaora hysoscella, the compass jellyfish, is a common species of jellyfish that inhabits coastal waters in temperate regions of the northeastern Atlantic Ocean, including the North Sea and Mediterranean Sea. In the past it was also recorded in the southeastern Atlantic, including South Africa, but this was caused by confusion with close relatives; C. africana, C. fulgida and an undescribed species tentatively referred to as "C. agulhensis".
Forage fish, also called prey fish or bait fish, are small pelagic fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food chain on plankton, often by filter feeding. They include particularly fishes of the order Clupeiformes, but also other small fish, including halfbeaks, silversides, smelt such as capelin and goldband fusiliers.
The European pilchard is a species of ray-finned fish in the monotypic genus Sardina. The young of the species are among the many fish that are sometimes called sardines. This common species is found in the northeast Atlantic, the Mediterranean, and the Black Sea at depths of 10–100 m (33–328 ft). It reaches up to 27.5 cm (10.8 in) in length and mostly feeds on planktonic crustaceans. This schooling species is a batch spawner where each female lays 50,000–60,000 eggs.
Marrus orthocanna species of pelagic siphonophore, a colonial animal composed of a complex arrangement of zooids, some of which are polyps and some medusae. Swimming independently in the mid-ocean, it lives in the Arctic and other cold, deep waters. It is a colonial creature that is born from a single egg which is fertilized. Later on, a protozoan forms that eventually grows to form more duplicating members of the colony. It belongs to the order Siphonophorae and the genus Marrus, which also includes M. antarcticus, M. claudanielis, and M. orthocannoides.
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.
Apolemia is a genus of siphonophores. It is the only genus in the monotypic family Apolemiidae.
Parasagitta setosa, the coastal arrow worm, is a small arrow worm in the family Sagittidae, previously referred to as Sagitta setosa. It is native to the northeastern Atlantic Ocean, the North Sea and the Mediterranean Sea, and also occurs in the Baltic Sea and the Black Sea.
The Diphyidae are a family of siphonophores. These are colonial siphonophores with two nectophores arranged one behind the other. The front one includes a somatocyst, while the hind one does not. The somatocyst often contains an oil droplet for buoyancy control. A nectosac in each nectophore allows the organism to swim efficiently.
Muggiaea is a genus of siphonophores in the family Diphyidae. Members of this family are colonial siphonophores with two nectophores arranged one behind the other, but in the genus Muggiaea, the posterior nectophore is absent. The anterior one has a complete dorsal ridge. The somatocyst is very close to the nectosac wall.
Muggiaea kochii is a species of small hydrozoan, a siphonophore in the family Diphyidae.
The lipid pump sequesters carbon from the ocean's surface to deeper waters via lipids associated with overwintering vertically migratory zooplankton. Lipids are a class of hydrocarbon rich, nitrogen and phosphorus deficient compounds essential for cellular structures. This lipid carbon enters the deep ocean as carbon dioxide produced by respiration of lipid reserves and as organic matter from the mortality of zooplankton.
Physonectae is a suborder of siphonophores. In Japanese it is called 胞泳.
Calycophorae is a suborder of Siphonophores alongside two other suborders Physonectae and Cystonectae. This suborder includes the giant siphonophore, ; one of the longest lengthwise extant creatures (40–50m). While the Physonectae have a pneumatophore, nectophore, and a siphosome, Cystonectae lack a nectophore, and Calycophorae lack a pneumatophore. From the bell-shaped nectophores, Physonectae and Calycophorae are called Codonophores or Greek for bell-bearers. The distribution, morphology, and behaviors of Calycophorae species are vast and greatly depend on the species. Calycophoraes typically consist of two nectophores with a siphosome that have many tentacles that grow out of the siphosome. The Calycophoraes move by propelling water out of the nectophore much like how jellyfishes move. The tentacles act as fishing nets where the nematocysts on the tentacles paralyze their prey which are then later fed on. Calycophorae have three life stages, which are the larval development stage, the polygastric stage, and the eudoxid maturation stage. Each Calycophorae colony forms from one fertilized egg.
Bassia is a monotypic siphonophore genus in the family Abylidae. The genus contains the single species Bassia bassensis.
Abylopsis tetragona is a species of siphonophore in the family Abylidae.
Lensia is a genus of hydrozoans belonging to the order Siphonoporae and the family Diphyidae. This genus is colonial and consists of many different types of highly specialized zooids. The genus Lensia was first established in 1932 by Dr. Arthur Knyvett Totton, who would also describe and add another 11 species during his career. As of March 2023, the genus consists of only 26 described and accepted species and an additional seven uncertain species, according to the World Register of Marine Species.