Umbellula
Genus of corals
From Wikipedia, the free encyclopedia
Umbellula is a genus of deep-sea cnidarians in the monotypic family Umbellulidae. Sea pens of this genus are known to be bioluminescent and hermaphroditic.
| Umbellula | |
|---|---|
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| Umbellula encrinus | |
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Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Subphylum: | Anthozoa |
| Class: | Octocorallia |
| Order: | Scleralcyonacea |
| Family: | Umbellulidae |
| Genus: | Umbellula Cuvier, [1797] |
| Type species | |
| Umbellula encrinus | |
| Species | |
| Synonyms[1] | |
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List
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Description
Species of Umbellula form colonial structures, which is common amongst pennatulacean octocorals (sea pens). Around the primary polyp distal region, secondary polyps form which are either larger autozooids (feeding polyps) or smaller siphonozooids (water circulation polyps).[2] The morphological adaptations of Umbellula species reflect adaptations to unique deep-sea environments, including differences in polyp arrangement and sclerite presence or absence. Species such as Umbellula encrinus having a typical cluster of autozooids,[3] while Umbellula pomona only possessing a terminal cluster of three autozooids.[4]
Most species of Umbellula have a strong, muscular peduncle which is used to anchor them in soft sediment, allowing them to inhabit areas of uniform benthic environments such as abyssal plains.[5]
Similarly to many deep-sea animals, some species of Umbellula can shift the color of their bioluminescence from blue to green using fluorescent proteins.[6][7]
The reproductive biology of sea pens in general remains poorly studied. A 2025 study examined 16 specimens across six distinct species of the genus Umbellula, and found gametogenic tissue in all specimens studied. Five of the six species were observed to be hermaphroditic, with two of the six being trioecious.[8]
Distribution
While there is a lack of conclusive study for Umbellula's distribution patterns, they can be found ranging from bathyal to abyssal depths, primarily in the Arctic Ocean, and also the northeast and southern Atlantic Ocean.[9][10]
Umbellula are known to be one of the only genera of sea pen found at depths of 4000m or greater.[11]
Taxonomy
Despite the unique morphology of this sea pen genus,[clarification needed] species identification is made difficult due to limited access to these organisms, and a traditional reliance on a small number of morphological characteristics, which has resulted in limited knowledge of intraspecific variation.[12]
The following species are considered valid by the World Register of Marine Species:[1]
- Umbellula ambigua Marion, 1906
- Umbellula antarctica Kükenthal, 1902
- Umbellula carpenteri Kölliker, 1880
- Umbellula dura Thomson & Henderson, 1906
- Umbellula durissima Kölliker, 1880
- Umbellula encrinus (Linnaeus, 1758)
- Umbellula guentheri Kölliker, 1880
- Umbellula hemigymna Pasternak, 1975
- Umbellula huxleyi Kölliker, 1880
- Umbellula koellikeri Kükenthal, 1902
- Umbellula koellikeri Thomson & Henderson, 1906 (unreplaced junior homonym of Umbellula koellikeri Kükenthal, 1902)
- Umbellula leptocaulis Kölliker, 1880
- Umbellula lindahli Kölliker, 1875
- Umbellula magniflora Kölliker, 1880
- Umbellula pellucida Kükenthal, 1902
- Umbellula pomona Risaro, Williams & Lauretta, 2020
- Umbellula purpurea Thomson & Henderson, 1906
- Umbellula radiata Thomson & Henderson, 1906
- Umbellula rigida Kükenthal, 1902
- Umbellula rosea Thomson & Henderson, 1906
- Umbellula spicata Kükenthal, 1902
- Umbellula thomsoni (Kölliker, 1874)
- Umbellula valdiviae Kükenthal, 1902
- Umbellula weberi Hickson, 1916
The following species are of uncertain validity, and many are nomen dubium:[1]
- Umbellula aciculifera J.S. Thomson, 1915
- Umbellula crassiflora Roule, 1905
- Umbellula elongata Thomson & Henderson, 1906
- Umbellula geniculata Studer, 1894
- Umbellula gilberti Nutting, 1908
- Umbellula grandiflora Kölliker
- Umbellula hendersoni Balss, 1906
- Umbellula indica Thomson & Henderson, 1906
- Umbellula intermedia Thomson & Henderson, 1906
- Umbellula jordani Nutting, 1908
- Umbellula loma Nutting, 1909
- Umbellula simplex Kölliker, 1880
Only an estimated ten[verification needed] of the forty-three described Umbellula species are considered valid members of the genus.[13]
Species of Umbellula were traditionally classified as a single group based on their morphology, but a 2013 molecular analysis that used the mitochondrial genes mtMutS and ND2 has revealed that the genus Umbellula is polyphyletic, and the species currently in the genus did not form a single clade (natural group).[14] These two distinct evolutionary lineages managed to have evolved similar appearances through evolutionary convergence. The following cladogram is based on that 2013 study:
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Ctenocella barbadensis | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Verrucella | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Umbellula monocephalus is now placed in Solumbellula.[15][16][17]
