Overview

Comprehensive Description

Pyrosoma is a genus of colonial, pelagic (open-ocean) tunicates. Colony size ranges from less than a centimeter to several meters in length. Each colony forms a transparent tube, closed at one end and open at the other, that is composed of hundreds or even thousands of outward-facing individuals (or zooids). These tiny zooids, each just millimeters long, are joined together by a gelatinous tunic. Water is drawn into each zooid through an oral siphon by beating cilia, creating a feeding current. Plankton are filtered out of the water and the depleted water is then expelled into the interior of the colony and out the posterior opening. This flow of water not only facilitates food acquisition, but also allows the colony to move by graceful jet propulsion, although Pyrosoma are mainly planktonic (passively free-floating).

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Shapiro, Leo

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Ecology

Habitat

Known from seamounts and knolls
  • Stocks, K. 2009. Seamounts Online: an online information system for seamount biology. Version 2009-1. World Wide Web electronic publication.
Creative Commons Attribution 3.0 (CC BY 3.0)

© WoRMS for SMEBD

Source: World Register of Marine Species

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Depth range based on 585 specimens in 20 taxa.
Water temperature and chemistry ranges based on 416 samples.

Environmental ranges
  Depth range (m): 0 - 5040
  Temperature range (°C): -1.566 - 28.884
  Nitrate (umol/L): 0.000 - 43.735
  Salinity (PPS): 30.220 - 38.998
  Oxygen (ml/l): 0.353 - 7.761
  Phosphate (umol/l): 0.073 - 3.390
  Silicate (umol/l): 0.499 - 167.288

Graphical representation

Depth range (m): 0 - 5040

Temperature range (°C): -1.566 - 28.884

Nitrate (umol/L): 0.000 - 43.735

Salinity (PPS): 30.220 - 38.998

Oxygen (ml/l): 0.353 - 7.761

Phosphate (umol/l): 0.073 - 3.390

Silicate (umol/l): 0.499 - 167.288
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

General Ecology

Ecology

Most Pyrosoma species are tropical. Unlike most tunicates, which are benthic (bottom-dwelling) and sessile (fixed in one place) as adults, Pyrosoma are pelagic at all life history stages, floating freely in the open ocean, sometimes in enormous numbers. One recent study off the coast of West Africa (Lebrato and Jones 2009) suggests that Pyrosoma tunicates that die and sink quickly to the bottom of the ocean may represent a major food resource for both benthic microbes and larger benthic organisms in the deep sea and should be included in models of large-scale cycling of elements such as carbon.

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Shapiro, Leo

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life History and Behavior

Behavior

Behaviour

A striking feature of Pyrosoma tunicates is their dramatic bioluminescence, which is visible for several meters underwater and appears in waves within the colony as flashing by individual zooids is triggered by flashes from their neighbors. Flashing can also be triggered by physical disturbance. When disturbed, individual zooids protect themselves by closing off their oral (intake) siphons, stopping the beating of their cilia, and emitting a flash of light. Neighbouring zooids detect the flash with their photoreceptors and respond in turn with protective responses and light emission. Protective responses thus spread by photic signalling and propagate from zooid to zooid through the colony (Mackie 1995).

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Shapiro, Leo

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Cyclicity

Pyrosoma may migrate hundreds of vertical meters each day. A study of Pyrosoma atlanticum occurring in offshore waters of the Ligurian Sea (Northwestern Mediterranean) in April of 1991 found that daytime depths and amplitudes of the diurnal migration were correlated with colony size. The amplitude of the migration ranged from 90 m for 3-mm-length colonies to 760 m for 51-mm-length colonies, with a mean amplitude of 410 m for the overall population pooled (Andersen and Sardou 1994). In the same study, the results of horizontal hauls at a given depth around sunrise and sunset revealed a marked diurnal symmetry of the migratory cycle relative to noon, and showed that migration of the population was not cohesive. For example, the larger the colonies, the later after sunset they reached the upper layers during their upward migration.

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Shapiro, Leo

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life Cycle

Pyrosoma are hermaphroditic, with each zooid producing both eggs and sperm. The fertilized egg gives rise to an embryo that develops into four attached zooids which subsequently reproduce asexually by budding off new zooids (Brooks 1906). This budding process is responsible for the growth of the colony. Thus, the life history of Pyrosoma includes both sexual and asexual phases.

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Shapiro, Leo

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Molecular Biology and Genetics

Molecular Biology

Genomic DNA is available from 2 specimens with morphological vouchers housed at British Antarctic Survey
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Ocean Genome Legacy

Source: Ocean Genome Resource

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Conservation

Threats

Pyrosoma are not known to face any special population threats.

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Shapiro, Leo

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Wikipedia

Pyrosome

Pyrosomes, genus Pyrosoma, are free-floating colonial tunicates that live usually in the upper layers of the open ocean in warm seas, although some may be found at greater depths. Pyrosomes are cylindrical- or conical-shaped colonies made up of hundreds to thousands of individuals, known as zooids. Colonies range in size from less than one centimeter to several metres in length.

Each zooid is only a few millimetres in size, but is embedded in a common gelatinous tunic that joins all of the individuals. Each zooid opens both to the inside and outside of the "tube", drawing in ocean water from the outside to its internal filtering mesh called the branchial basket, extracting the microscopic plant cells on which it feeds, and then expelling the filtered water to the inside of the cylinder of the colony. The colony is bumpy on the outside, each bump representing a single zooid, but nearly smooth, though perforated with holes for each zooid, on the inside.

Pyrosomes are planktonic, which means their movements are largely controlled by currents, tides, and waves in the oceans. On a smaller scale, however, each colony can move itself slowly by the process of jet propulsion, created by the coordinated beating of cilia in the branchial baskets of all the zooids, which also create feeding currents.

Pyrosomes are brightly bioluminescent, flashing a pale blue-green light that can be seen for many tens of metres. The name Pyrosoma comes from the Greek (pyro = "fire", soma = "body"). Pyrosomes are closely related to salps, and are sometimes called "fire salps". Sailors on the ocean are occasionally treated to calm seas containing many pyrosomes, all luminescing on a dark night.

Bioluminescence[edit]

Although many planktonic organisms are bioluminescent, pyrosome bioluminescence is unusual in its brilliance and sustained light emission,[1] and evoked the following comment when seen by scientist T.H. Huxley at sea:

"I have just watched the moon set in all her glory, and looked at those lesser moons, the beautiful Pyrosoma, shining like white-hot cylinders in the water" (T.H. Huxley, 1849).[2]

Section through the wall of a pyrosome (magnified) showing a single layer of ascidiozooids; br) branchial orifice; at) atrial orifice; tp) process of the test; br s) branchial sac

Pyrosomes often exhibit waves of light passing back and forth through the colony, as each individual zooid detects light and then emits light in response. Each zooid contains a pair of light organs located near the outside surface of the tunic, which are packed with luminescent organelles that may be intracellular bioluminescent bacteria.[3] The waves of bioluminescence that move within a colony are apparently not propagated through neurons, but by a photic process.[3] Flashing zooids not only stimulate other zooids within the colony to bioluminesce, but nearby colonies will also display bioluminescence in response. Colonies bioluminesce in response to mechanical stimulation (touch), as well as to light.[1]

Species[edit]

Pyrosome found floating dead in 2010 near the Gulf of Mexico.

The following species are accepted as valid by the World Register of Marine Species:[4]

References[edit]

  1. ^ a b Bowlby, M.R.; E.A. Widder and J.F. Case (1990). "Patterns of stimulated bioluminescence in two pyrosomes (Tunicata: Pyrosomatidae)". Biological Bulletin (Marine Biological Laboratory) 179 (3): 340–350. doi:10.2307/1542326. JSTOR 1542326. 
  2. ^ Huxley, J. (1936). T.H. Huxley's Diary of the Voyage of H.M.S. Rattlesnake. Garden City, New York: Doubleday. 
  3. ^ a b Mackie, G.O.; Bone, Q. (1978). "Luminescence and associated effector activity in Pyrosoma (Tunicata: Pyrosomida)". Proceedings of the Royal Society B 202 (1149): 483–495. doi:10.1098/rspb.1978.0081. 
  4. ^ Pyrosoma World Register of Marine Species. Retrieved 2011-11-12.
  • Bone, Q. editor (1998) The Biology of Pelagic Tunicates. Oxford University Press, Oxford. 340 pp.
Creative Commons Attribution Share Alike 3.0 (CC BY-SA 3.0)

Source: Wikipedia

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!