Obelia
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (June 2013) |
Obelia | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Cnidaria |
Class: | Hydrozoa |
Order: | Leptothecata |
Family: | Campanulariidae |
Genus: | Obelia Peron and Lesueur, 1810 |
Species | |
Obelia is a genus of
Obelia is also called sea fur.[3]
Obelia has a worldwide distribution except the high-Arctic and Antarctic seas.[4] and a stage of Obelia species are common in coastal and offshore plankton around the world.[5] Obelia are usually found no deeper than 200 metres (660 ft) from the water's surface, growing in intertidal rock pools and at the extreme low water of spring tides.
Life cycle
The polyp colony reproduces
The next generation of the life cycle begins when the medusae are released from the gonozooids, producing free swimming male only medusae velum with
The planulae are free-swimming for a while but eventually attach themselves to some solid surface, where they begin their reproductive phase of life. Once attached to a substrate, a planula quickly develops into one feeding polyp. As the polyp grows, it begins developing branches of other feeding individuals, thus forming a new generation of polyps by asexual budding.
Structure
Through its life cycle, Obelia take on two forms:
Phylogeny
Estimates of divergence times and distinctive haplotypes provide evidence of glacial refugia around Iceland and southeastern Canada. In one study, O. geniculata was first documented in these areas in the 1990s but were later found in Massachusetts and Japan in the 2000s. There are three reciprocally monophyletic clades of Obelia, one branch for the North Atlantic, one for Japan, and one for New Zealand.[6] There seems to be an ancestral haplotype that occurs in the North Atlantic populations from Massachusetts, New Brunswick, and Iceland. The population from Woods Hole, MA shows less genetic diversity than the New Brunswick population. The more recent expansion of these haplotypes demonstrates the southward movement of hydroid populations, possibly due to climate change. The North Atlantic populations contain ancestral haplotypes, which differ from the populations in Japan and New Zealand. Pacific populations have more haplotype diversity than all four of the North Atlantic populations, which indicates that the North Atlantic population is more recently established than the Pacific population.[6] The minimum estimated age of the New Brunswick population is between 47 and 143 thousand years old. Including the Massachusetts population, this number is between 82 and 150 thousand years, but Iceland has the oldest estimated population with the minimum age ranging from 68 to 204 thousand years old.[6]
Obelia are distinguishable from others in Campanulariidae from their size in length and diameter, as well as their smaller hydrothecal cusps and relatively thinner perisarc thickness. Some morphological traits are hard to distinguish across species, so observing a combination of these traits will help with identification. Other useful observable characteristics are branching pattern of colonies and length of trophosome. There are variations and exceptions to these, which makes identification even more difficult.[7] O. geniculata is characterized by a thicker perisarc with more variation that other species of Obelia. O. longissima have longer first and second order branches, in addition to a greater variation in hydrothecal cusp length than others in the genus. O. bidentata differs from the previous species due to their more cylindrical and longer hydrothecal cusps.[7]
Notes
- ^ S2CID 89441197.
- ^ .
- ISBN 9788171338962.
- ^ Cornelius, P.F.S., 1990a. European Obelia (Cnidaria, Hydroida): systematics and identification. Journal of Natural History 24: 535-578.
- ^ Cornelius, P.F.S., 1995b. North-West European thecate hydroids and their Medusae. Part 2. Synopses of the British Fauna (New Series), No 50.
- ^ a b c Govindarajan, AF; Halanych, KM; Cunningham, CW (17 August 2004). "Mitochondrial evolution and phylogeography in the hydrozoan Obelia geniculata (Cnidaria)" (PDF). Retrieved 7 November 2022.
- ^ .
References
- F. Boero, C. Bucci, A.M.R. Colucci, C. Gravili, L. Stabili; Obelia (Cnidaria, Hydrozoa, Campanulariidae): a microphagous, filter-feeding medusa, Web of Science, 2007. https://doi.org/10.1111/j.1439-0485.2007.00164.x
- B. Grzimek; Grzimek's Animal Life Encyclopedia (Volume 1: Lower Animals); Van Nostrand Reinhold Company.
- D. George; Marine Life: An Illustrated Encyclopedia of Invertebrates in the Sea; Wiley-Interscience Publication.
- E.P Solomon, L.R Berg, and D.W Martin (editor); ISBN 0-534-39175-3(6th edition, hardcover, 2002).
- K. Sutherland, Prey capture by the cosmopolitan hydromedusae, Obelia spp. in the viscous regime, Association of Limnology and Oceanography, 2016. https://doi.org/10.1002/lno.10390
- J. Moore (editor); An Introduction to the Invertebrates; Cambridge University Press
- L. Gilbertson; Zoology Laboratory Manual; The McGraw-Hill Companies, Inc; ISBN 0-07-237716-X(4th edition, 1999)
- Some taxonomic information also came from National Center for Biotechnology Information (NCBI)[1]
- AF. Govindarajan, KM Halanych, CW Cunningham; Mitochondrial evolution and phylogeography in the hydrozoan Obelia geniculata (Cnidaria), 2004.
- A. Cunha, A. Collins, A. Marques; When morphometry meets taxonomy: morphological variation and species boundaries in Proboscoida (Cnidaria:Hydrozoa), Zoological Journal of the Linnean Society. https://doi.org/10.1093/zoolinnean/zlz166