| Pyrosomatidae Temporal range:
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|---|---|
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| Pyrosoma atlanticum | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Tunicata |
| Class: | Thaliacea |
| Order: | Pyrosomatida Jones, 1848[1] |
| Family: | Pyrosomatidae Lahille, 1888 |
| Genera[3] | |
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Pyrosomes are free-floating colonial tunicates in family Pyrosomatidae. There are three genera, Pyrosoma, Pyrosomella and Pyrostremma, and eight species.[3][4] They usually live in the upper layers of the open ocean in warm seas, although some may be found at greater depths.[4]
Pyrosomes form cylindrical or cone-shaped colonies up to 18 m (60 ft) long,[5] 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. They are commonly called "sea pickles".[6][7] Other nicknames include "sea worms", "sea squirts", "fire bodies", and "cockroaches of the sea".[8]
Each zooid is a few millimetres in size, but is embedded in a common gelatinous tunic that joins all of the individuals.[6] 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, although perforated with holes for each zooid, on the inside.[5][8]
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.[8]
Pyrosomes are brightly bioluminescent, flashing a pale blue-green light that can be seen for many tens of metres. Pyrosomes are closely related to salps, and are sometimes called "fire salps". Sailors on the ocean occasionally observe calm seas containing many pyrosomes, all luminescing on a dark night.[5][8]
Pyrosomes feed through filtration and they are among the most efficient filter feeders of any zooplankton species.[9]
- ^ "Pyrosomatida". Catalogue of Life. Species 2000: Leiden, the Netherlands. Retrieved 29 September 2024.
- ^ WoRMS. "Pyrosoma Péron, 1804". World Register of Marine Species. Retrieved 20 September 2024.
- ^ a b WoRMS. "Pyrosomatidae Lahille, 1888". World Register of Marine Species. Retrieved 29 September 2024.
- ^ a b Lilly, Laura E.; Suthers, Iain M.; Everett, Jason D.; Richardson, Anthony J. (2023). "A global review of pyrosomes: Shedding light on the ocean's elusive gelatinous "fire-bodies"". Limnol. Oceanogr. Lett. 8 (6): 812–829. Bibcode:2023LimOL...8..812L. doi:10.1002/lol2.10350.
- ^ a b c Garber, Megan (August 2, 2013). "12 Reasons Pyrosomes Are My New Favorite Terrifying Sea Creatures". The Atlantic.
- ^ a b "Blob-like intruders infesting pacific coast". 22 June 2017.
- ^ "Newsweek: Mysterious Sea Pickles invading West Coast in bizarre bloom". Newsweek. 22 June 2017.
- ^ a b c d Guo, Demi (February 20, 2019). "See the giant 'sea worm' filmed off the coast of New Zealand". National Geographic. Archived from the original on February 20, 2019.
- ^ Henschke, Natasha; Pakhomov, Evgeny A.; Kwong, Lian E.; Everett, Jason D.; Laiolo, Leonardo; Coghlan, Amy R.; Suthers, Iain M. (May 2019). "Large vertical migrations of Pyrosoma atlanticum play an important role in active carbon transport". Journal of Geophysical Research: Biogeosciences. 124 (5): 1056–1070. Bibcode:2019JGRG..124.1056H. doi:10.1029/2018JG004918. hdl:10453/139295.