Mastigias papua
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Mastigias papua , Monterey Bay Aquarium, Monterey, California |
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| Mastigias papua | ||||||||||||
| Lesson , 1830 |
Mastigias papua is an umbrella jellyfish (Scyphozoa) thatoccurs in lagoons and island lakesin the Pacific Ocean . Due to its abundance in the Ongeim'l Tketau (jellyfish lake ) on theisland of Eil Malk ( Palau ) offthe island of Koror , thespecies has achieveda certain level of awareness among those interested in diving and in the media. The taxonomic status of the species and its widespread distribution is discussed on the basis of new morphological and molecular data. It is more likely a species complex of several cryptic species.
features
The hemispherical umbrella can reach a diameter of up to 200 mm (ssp. Salii ). The basic color is bluish, the surface is covered with fine warts. However, the basic color of individual subspecies has changed to light brown due to the inclusion of zooxanthellae. Deep furrows are formed between the eight flaps. The mouth arms reach about half the length of the umbrella diameter. The upper third of an arm is simple, the lower two thirds three-winged. The arms usually end in a club-like thickening. The arms can be greatly reduced in some subspecies. The rhopalial canals are slender and branch out.
Distribution, occurrence and way of life
According to the data published so far, the species is distributed from Indonesia in the west, via the Philippines to Japan , and in the south via Papua New Guinea to Palau . If the more recent molecular biological data are confirmed, the range of the actual Mastigias papua would have to be severely restricted. The animals live in lagoons, brackish water lakes, marine lakes and in mangroves.
Taxonomy and nomenclature
The distribution and extent of the species has been called into question by new morphological and molecular biological studies. The species was first comprehensively revised by Alfred Goldsborough Mayer in 1910. The holotype of the species comes from Waigeo , the largest island of the four main islands of the Raja Ampat group of islands off western New Guinea ( Indonesia ). So far no specimen of the Locus typicus could be examined with newer methods. However, recent investigations of other localities cast doubt on the previously assumed wide geographical distribution of the species. Dawson (2004, 2005) found large molecular biological and also morphological differences as well as differences in the way of life of the populations of Mastigias papua in the various marine lakes and the neighboring open lagoons on Palau, which in any case justify a separation at the subspecies level. Specimens from the mouth of the Berau (eastern Kalimantan ) and from Tufi ( Oro Province, Papua New Guinea) also show a very large molecular genetic distance to the populations on Palau, which are at species level before. the localities of the three populations studied (Berau, Tufi and Palau), however, are each more than 1000 km from the locus typicus of Mastigias papua removed. Without material from the type locality, it is currently not possible to decide which of the three populations studied Mastigias papua is , or whether there is even a fourth species hidden in the species complex that has hitherto been referred to as Mastigias papua . It is therefore more likely that the populations of Palau are not part of Mastigias papua , but represent a species of their own To be able to go one step is also an investigation of the other species of the genus Mastigias ( M. albipunctata Stiasny, 1920, M. andersoni Stiasny, 1926, M. gracilis Vanhöffen, 1888), M. ocellatus (Modeer, 1791), M. pantherinus Haeckel, 1880, M. roseus (Reynaud, 1830) and M. sidereus Chun, 1896), which from the Ind and western Pacific have been described due to morphological differences. In addition, it must be taken into account that Alfred Goldsborough Mayer in his comprehensive work "Medusae of the World" synonymized another species (from Japan) and a variety with Mastigias papua , which, according to the above experience, could definitely be independent species. No data are yet available on this either. Mastigias papua in its current form is a species complex of at least three, more likely even five or more cryptic species. Therefore, the subspecies identified by Dawson (2005) in five different marine lakes on Palau are called Mastigias cf. papua ssp. designated.
- Mastigias cf. papua ssp. remengesaui Dawson, 2005 (Uet era Ongael, Ongael, Koror, Palau). The species is characterized by numerous white spots of different sizes on the exumbrella. Inter- and perradial canals, the parts of the tentacles near the mouth and their tips are often colored blue. The shade has a brown base color, which is caused by the zooxanthellae. The planktonic medusas grow to a size of just over 15 cm. They are only occasionally frequent, but are also completely absent at certain times. They can be found from about 4 m depth to the lake level.
- Mastigias cf. papua ssp. nakamurai Dawson, 2005 (Goby Lake, Ngermeuangel, Koror, Palau) The brown basic color is complemented by blue spots in small medusa. With smaller and larger medusas there are also yellow spots on the edge of the screen. The medusas are a little over 15 cm tall. They occur all year round in the water column from 0 to 7 m.
- Mastigias cf. papua ssp. etpisoni Dawson, 2005 ("Jellyfish Lake", Ongeim'l Tketau , Mecherchar, Koror, Palau). The medusa are brown, without blue pigmentation, and there are seldom fine white spots. Otherwise there are no stains. The thickened end portions of the eight oral arms are relatively short and wide. The largest medusas grow up to 23 cm. The medusas are planktonic and usually present all year round in the water column from 0 to 13 m depth.
- Mastigias cf. papua ssp. saliii Dawson, 2005 (Clear Lake, Koror, Palau). The light brown basic color caused by the zooxanthellae is complemented by a blue pigmentation in the inter- and perradial canals. The thickened end portions of the eight oral arms are short to medium long and lanceolate in shape. The medusas are up to 20 cm tall. They live at depths of 0 to 9 meters and are usually quite common. But they can also be completely absent. The salinity of the water at the time of the appearance of the medusa was significantly reduced (22.6–28.1 psu). The polyps are found on decomposing leaves at a depth of 6 to 7 meters.
- Mastigias cf. papua ssp. remeliiki Dawson, 2005 (Uet era Ngermeuangel, Ngermeuangel, Koror, Palau). The basic color is golden brown due to the embedded zooxanthellae. Most specimens are missing spots on the exumbrella. But if there are, then they are often and irregularly shaped. The blue pigmentation is completely absent. The thickened end parts of the eight oral arms are paddle-shaped, lanceolate or rarely three-pointed and always quite short. The medusas are about 8 to 12 cm tall. The medusas occur all year round in the water column (0 to 16 m). The water is mostly slightly brackish (24.5 to 31.5 psu). The polyps were found attached to hard substrate, decaying leaves and wood in about 6 to 16 m water depth.
The subspecies emerged from the isolation of populations of the lagoon species from rising sea levels after the last interglacial period. The depressions are connected to the sea level via karst cavities; the lake level corresponds roughly to the sea level. This means that the deepest lakes ("Jellyfish Lake", Ongeim'l Tketau: 60 m deep) are also the oldest lakes and cannot be older than 12,000 years.
literature
- Michael N Dawson: Morphological variation and systematics in the Scyphozoa: Mastigias (Rhizostomeae, Mastigiidae) - a golden unstandard ?. In: Hydrobiologia. 537, 2005, pp. 185-206, doi: 10.1007 / s10750-004-2840-8 . PDF
- Michael N Dawson: Five new subspecies of Mastigias (Scyphozoa: Rhizostomeae: Mastigiidae) from marine lakes, Palau, Micronesia. In: Journal of the Marine Biological Association of the UK. 85, 2005, pp. 679-694, doi: 10.1017 / S0025315405011604 . PDF
- Paul Lassenius Kramp: Synopsis of the Medusae of the World . Journal of the Marine Biological Association of the United Kingdom, 40, 1961, pp. 359/60.
Web links
- Meerwasser-lexikon.de: Mastigias papua
- Monterey Bay Aquarium: Spotted Jelly
supporting documents
Individual evidence
- ^ M. N Dawson: From The Cover: Rapid evolutionary radiation of marine zooplankton in peripheral environments. In: Proceedings of the National Academy of Sciences. 102, 2005, pp. 9235-9240, doi: 10.1073 / pnas.0503635102 .