''Pyrosoma atlanticum'' is a

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of marine

colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 au ...

tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ...

in the class

Thaliacea The Thaliacea comprise a class of marine animals within the subphylum Tunicata. Unlike their benthic relatives the ascidians, thaliaceans are free-floating (pelagic) for their entire lifespan. The group includes species with complex life cycle ...

found in temperate waters worldwide. The name of the genus comes from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

words ''pyros'' meaning 'fire' and ''soma'' meaning 'body', referring to the bright bioluminescence sometimes emitted.''Pyrosoma atlanticum'' (Peron, 1804) : Pyrosome
The JelliesZone. Retrieved 2011-11-10. The specific epithet ''atlanticum'' refers to the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

, from where the first specimen of the species was collected for scientific description; it was described in 1804 by

François Péron François Auguste Péron (22 August 1775 – 14 December 1810) was a French naturalist and explorer. Life Péron was born in Cérilly, Allier, in 1775, the son of a tailor (not a harness maker as is frequently asserted). Although intended for ...

, a French naturalist.

Description

A colony of ''P. atlanticum'' is cylindrical and can grow up to long and wide. The constituent

zooid A zooid or zoöid is a single animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zoo ...

s form a rigid tube, which may be pale pink, yellowish, or bluish. One end of the tube is narrower and is closed, while the other is open and has a strong diaphragm. The outer surface or test is gelatinised and dimpled with backward-pointing, blunt processes. The individual zooids are up to long and have a broad, rounded branchial sac with

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

slits. Along the side of the branchial sac runs the

endostyle The endostyle is an anatomical feature found in invertebrate chordates and larval lampreys. It is an organ which assists chordates in filter-feeding. It is found in adult urochordates and cephalochordates, as well as in the larvae of the vertebra ...

, which produces

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...

filters. Water is moved through the gill slits into the centre of the cylinder by cilia pulsating rhythmically.

Plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

and other food particles are caught in mucus filters in the processes as the colony is propelled through the water. ''P. atlanticum'' is bioluminescent and can generate a brilliant blue-green light when stimulated.''Pyrosoma atlanticum''
Marine Species Identification Portal. Retrieved 2011-11-11.

Distribution and habitat

''P. atlanticum'' is found in temperate waters in all the world's oceans, usually between 50°N and 50°S. It is most plentiful at depths below 250 m (800 ft).''Pyrosoma atlanticum'' - Péron, 1804
SeaLifeBase. Retrieved 2011-11-11. Colonies are pelagic and move through the water column. They undergo a large diurnal migration, rising toward the surface in the evening and descending around dawn. Large colonies may rise through a vertical distance of 760 m (2,500 ft) daily, and even small colonies a few millimetres long can cover vertical distances of 90 m (300 ft).

Biology

A study in the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by t ...

comparing different

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

organisms found that colonies of ''P. atlanticum'' were the most efficient grazers of particles above 10 µm in diameter, catching a higher proportion of the particles than other grazers. This implies the species uses high biomass intake as a strategy, rather than investing in energy-conservation mechanisms. Growth occurs by new rings of zooids being budded off around the edge of the elongating colony. A pair of luminescent organs is on either side of the inlet siphon of each zooid. When stimulated, these turn on and off, causing rhythmic flashing. No neural pathway runs between the zooids, but each responds to the light produced by other individuals, and even by light from other nearby colonies. ''P. atlanticum'' remains as one of the least studied planktonic grazers, according to a 2021 study. In the study, the researchers took samples of the pyrosome's microbiome. The results of the study found that a possible source of bioluminescence in ''P. atlanticum'' is the abundance of '' Photobacterium'' in its microbiome. However, there is still debate, as a 2020 study found a potential endogenous pyrosome luciferase in the organism's transcriptome homologous to ''Renilla'' luciferase (RLuc). Further study of the luciferase showed that it reacted with

coelenterazine Coelenterazine is a luciferin, a molecule that emits light after reaction with oxygen, found in many aquatic organisms across eight phyla. It is the substrate of many luciferases such as '' Renilla reniformis'' luciferase (Rluc), ''Gaussia'' lucif ...

to produce light, much like RLuc.

Ecology

Five specimens of the

penaeid Penaeidae is a family of marine crustaceans in the suborder Dendrobranchiata, which are often referred to as penaeid shrimp or penaeid prawns. The Penaeidae contain many species of economic importance, such as the tiger prawn, whiteleg shrimp, ...

shrimp '' Funchalia'' were found living inside colonies of ''P. atlanticum''. Other

amphipods Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far describ ...

also lived there, including the hyperiids '' Phronima'' and '' Phronimella'' spp.

Predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

of ''P. atlanticum'' include various bony fishes, such as the spiky oreo, the big-eyed cardinalfish, and the

pelagic butterfish The pelagic butterfish, ''Schedophilus maculatus'', is a medusafish Medusafishes are a family, Centrolophidae, of percomorph fishes. The family includes about 31 species. They are found in temperate and tropical waters throughout the world. Y ...

dolphin A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the ...

s, and

whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

s such as the sperm whale and

giant beaked whale The four-toothed whales or giant beaked whales are beaked whales in the genus ''Berardius''. They include Arnoux's beaked whale (''Berardius arnuxii'') in cold Southern Hemispheric waters, and Baird's beaked whale (''Berardius bairdii'') in t ...

Synonyms

* ''Dipleurosoma ellipticum'' Brooks, 1906 – genus transfer and junior synonym * ''Pyrosoma atlanticum dipleurosoma'' Metcalf & Hopkins, 1919 – junior synonym * ''Pyrosoma atlanticum echinatum'' Metcalf & Hopkins, 1919 – junior synonym * ''Pyrosoma atlanticum'' f. ''elegans'' Lesueur, 1815 – junior synonym * ''Pyrosoma atlanticum hawaiiense'' Metcalf & Hopkins, 1919 – junior synonym * ''Pyrosoma atlanticum intermedium'' Metcalf & Hopkins, 1919 – junior synonym * ''Pyrosoma atlanticum paradoxum'' Metcalf & Hopkins, 1919 – junior synonym * ''Pyrosoma atlanticum triangulum'' Neumann, 1913 – junior synonym * ''Pyrosoma atlanticum'' var. ''giganteum'' Lesueur, 1815 – junior synonym * ''Pyrosoma atlanticum'' var. ''levatum'' Seeliger, 1895 – junior synonym * ''Pyrosoma atlanticum'' var. ''tuberculosum'' Seeliger, 1895 – junior synonym * ''Pyrosoma benthica'' Monniot C. & Monniot F., 1966 – junior synonym * ''Pyrosoma elegans'' Lesueur, 1813 – junior synonym * ''Pyrosoma ellipticum'' (Brooks, 1906) – junior synonym * ''Pyrosoma giganteum'' Lesueur, 1815 – junior synonym * ''Pyrosoma giganteum'' var. ''atlanticum'' Péron, 1804 – status change * ''Pyrosoma rufum'' Quoy & Gaimard, 1824 – junior synonym * ''Pyrosoma triangulum'' Neumann, 1909 – junior synonym

References

External links

* {{Taxonbar, from=Q4927517 Thaliacea Fauna of the Atlantic Ocean Fauna of the Indian Ocean Fauna of the Pacific Ocean Bioluminescent animals Animals described in 1804 Taxa named by François Péron