Placentonema gigantissima

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Placentonema gigantissima
Systematics
Order : Rhabditida
Superfamily : Habronematoidea
Family : Tetrameridae
Subfamily : Crassicaudinaeae
Genre : Placentonema
Type : Placentonema gigantissima
Scientific name of the  genus
Placentonema
Gubanow, 1951
Scientific name of the  species
Placentonema gigantissima
Gubanow , 1951

Placentonema gigantissima is a species of roundworm from the order Rhabditida that parasitizes in the placentae of sperm whales (Physeter macrocephalus) . Placentonema gigantissima is the longest known nematode species with a length of up to nine meters in females.

features

In the genus Placentonema , the males have two lateral caudal alae and the female 32 uteri . In contrast, the alae are absent in the males of the genus Crassicauda , and their females have only two uteri.

The bodies of the worms are extremely elongated and encased in a transparent cuticle that is only cross-striated at the head end. The oval mouth opening, which is very small with a fraction of a millimeter, has two simple lateral lips, each with two papillae. The throat is cylindrical and in the esophagus the short muscular and the approximately 60 to 70 millimeters long glandular part are clearly separated from each other. Male placentonema gigantissima reach a length of up to 3.75 meters with a diameter of eight to nine millimeters. Your body ends bluntly and rounded at the belly and has alae on both sides. The cloaca is 1.4 to 1.6 millimeters from the back of the body. The female animals are up to nine meters long with a diameter of up to 2.5 centimeters. This makes them by far the longest and, with a length to diameter ratio of more than 350 to 1, exceptionally slender nematodes . At the end of the body there is a pear-shaped area about 11 millimeters long, the anal opening is 0.8 to 1 millimeter in front of the end of the body. The reproductive tract consists of 32 uteri, which are connected to the vulva by the short vagina about 12.4 to 14.8 millimeters in front of the anus. The uteri may contain oval eggs 0.049 mm long and 0.030 mm in diameter. Each egg contains a fully formed juvenile worm.

distribution

The geographical range of Placentonema gigantissima as a mandatory species parasitizing the sperm whale is limited to the range of its host, which occurs in all oceans . This has a species-specific distribution with a preference for the tropics and subtropics by the females and the temperate latitudes by the bulls, who also advance into the polar region. Since Placentonema gigantissima is only known from female sperm whales, it is possible that the species occurs predominantly in tropical and subtropical waters. In the literature, in addition to the type location of the waters around the Kuril Islands , California and the Canadian Pacific coast were named as locations for Placentonema gigantissima . The composition of the tapeworm fauna of the small intestine and bile ducts of the sperm whale depends to a large extent on the habitat. It cannot be ruled out that Placentonema gigantissima is only widespread in part of the population of the sperm whale, and thus has a lower geographical spread than the sperm whale.

Way of life

Little is known about the way of life of Placentonema gigantissima . Sperm whales are pregnant for about 16 months. The fetuses of toothed whales almost always develop in the left uterine horn , regardless of the ovary ovulated has. In the right horn of the uterus, along with most of the placenta, there is also the habitat of Placentonema gigantissima . The placental tissue of whales is a diffuse epithelochordial mass, similar to that of horses, pigs and other odd-toed ungulates. The parasite lives in the transparent shell of the placenta and uterus of female sperm whales. Information in the literature published between 1955 and 2015, according to which Placentonema gigantissima or a species of the genus Placentoma was found in the mammary glands and subcutaneous tissue of sperm whales or white-flanked porpoises , probably refer to species of the closely related genus Crassicauda . These colonize the mammary glands of both sexes and nodes in the subcutaneous tissue of the females of the white-flanked porpoise and other whales.

Nothing is known about the reproduction of the parasite or its transmission, except the existence of eggs. There is no evidence of a direct damaging effect of Placentonema gigantissima on the fetus of the whale, but a strong infestation could indirectly affect it through food competition and an immune reaction. On the other hand, the huge growth of Placentonema gigantissima prevents mass infestation, which in other endoparasites can disrupt the function of infected organs to the point of failure.

The enormous growth in length of Placentonema gigantissima could be made possible by the good supply of nutrients in the placenta and the endometrium , the absorption of nutrients through the skin and the protection provided by the placental barrier . A comparable gigantic growth also occurs with other endoparasites and stationary ectoparasites, when easily digestible nutrients are available in abundance.

Hazard and protection

As an obligatory parasite of the sperm whale, Placentonema gigantissima is subject to the same threats as its host. The IUCN carried out an assessment of the threat to the existence of the population in 2008, which was updated in 2019. After that, the population of the sperm whale is endangered (VU - Vulnerable) . However, the parasite also benefits from the measures taken to protect the sperm whale.

Taxonomy

The first description of Placentonema gigantissima was published in 1951 by the Soviet helminthologist Nikolai Mikhailovich Gubanov in the reports of the Academy of Sciences of the USSR .

The roundworms of the family Tetrameridae within the order Rhabditida are predominantly parasites of birds and whales . The family consists of the subfamilies Geopetitinae and Tetramerinae, parasites of birds, and the Crassicaudinaeae , which parasitize on whales . The Crassicaudineae include the genera Crassicauda , parasites of the urinary and reproductive system and the paranasal sinuses of whales, and the monotypical genus Placentonema .

Web links

Individual evidence

  1. ^ Leo Margolis, Gordon C. Pike: Some helminth Parasites of Canadian Pacific whales . In: Journal of the Fisheries Research Board of Canada . tape 12 , no. 1 , 1955, pp. 97-120 , doi : 10.1139 / f55-008 .
  2. ↑ a b Nikolai Michailowitsch Gubanow : Гигантская нематода из плаценты китообразных - Placentonema gigantissima nov. gen., nov. sp. (A giant nematode from the placenta of whales - Placentonema gigantissima nov. Gen., Nov. Sp.) . In: Доклады Академии Наук СССР (Doklady Akademii Nauk SSSR, reports of the Academy of Sciences of the USSR) . tape 77 , no. 6 , 1951, ISSN  0002-3264 , pp. 1123-1125 ( first description ).
  3. ↑ István Andrássy: Two unusually slender nematode species of Trischistoma Cobb, 1913 (Enoplida: Tripylidae) . In: Nematology . tape 13 , no. 5 , 2011, p. 561-567 , doi : 10.1163 / 138855410X533635 .
  4. ^ A b J. R. Geraci, Murray D. Dailey, DJ St. Aubin: Parasitic Mastitis in the Atlantic White-Sided Dolphin, Lagenorhgnchus acutus, as a Probable Factor in Herd Productivity . In: Journal of the Fisheries Research Board of Canada . tape 35 , no. 10 , 1978, p. 1350-1355 , doi : 10.1139 / f78-210 .
  5. ↑ Murray D. Dailey, Wolfgang K. Vogelbein: Parasite Fauna of Three Species of Antarctic Whales with Reference to Their Use as Potential Stock Indicators . In: Fishery Bulletin . tape 89 , no. 3 , 1991, pp. 355-365 . Digitized http: //vorlage_digitalisat.test/1%3D~GB%3D~IA%3Dfisherybulletin890104unit~MDZ%3D%0A~SZ%3D~doppelseiten%3D~LT%3D~PUR%3D
  6. ↑ Leo Margolis, Murray D. Dailey: Revised Annotated List of Parasites from Sea Mammals Caught Off the West Coast of North America (= US Department of Commerce and National Oceanic and Atmospheric Administration [Eds.]: NOAA Technical Report . NMFS SSRF-647 ). National Marine Fisheries Service, Seattle, WA 1972. Digitized http: //vorlage_digitalisat.test/1%3D~GB%3D~IA%3Dnoaatechnicalrep647unit~MDZ%3D%0A~SZ%3D~doppelseiten%3D~LT%3D~PUR%3D
  7. ^ Leo Margolis, Hisao P. Arai: Parasites of Marine Mammals (= Murray J. Kennedy [Ed.]: Synopsis of the Parasites of Vertebrates of Canada ). Alberta Agriculture. Animal Health Division, Edmonton 1989. Digitized http: //vorlage_digitalisat.test/1%3D~GB%3D~IA%3Dsynopsisofparasi00marg~MDZ%3D%0A~SZ%3D~doppelseiten%3D~LT%3D~PUR%3D
  8. ^ A b c Richard H. Lambertsen: Natural disease problems of the sperm whale . In: Bulletin de l'Institut Royal des Sciences Naturelles de Belgique. Biology . 67 Supplement, 1997, p. 105-112 .
  9. ↑ Everhard Johannes Slijper: Giants of the Sea. A biology of whales and dolphins (=  Karl von Frisch [Hrsg.]: Understandable Science . Eightieth Volume). Springer, Berlin a. a. 1962, ISBN 978-3-540-02919-9 , pp. 100 .
  10. ^ A b Mariano Dueñas Díaz, Fabiana B. Drago, Verónica Núñez: A new species of Microtetrameres (Nematoda, Tetrameridae) parasitizing Buteogallus urubitinga (Aves, Accipitridae) from northeastern Argentina . In: Anais da Academia Brasileira de Ciências . tape 90 , no. 3 , 2018, doi : 10.1590 / 0001-3765201820170967 .
  11. ↑ a b Carlos Hermosilla et al .: Endoparasite survey of free-swimming baleen whales (Balaenoptera musculus, B. physalus, B. borealis) and sperm whales (Physeter macrocephalus) using non / minimally invasive methods . In: Parasitology Research . No. 115 , 2016, p. 889-896 , doi : 10.1007 / s00436-015-4835-y .
  12. ↑ Thomas A. Jefferson: Phocoenoides dalli . In: Mammalian Species . No. 319 , 1988, pp. 1-7 , doi : 10.2307 / 3504170 .
  13. ↑ Carlos Hermosilla et al .: Occurrence of anthropozoonotic parasitic infections and faecal microbes in free-ranging sperm whales (Physeter macrocephalus) from the Mediterranean Sea . In: Parasitology Research . No. 117 , 2018, p. 2531-2541 , doi : 10.1007 / s00436-018-5942-3 .
  14. ^ A b C. Dieter Zander: Parasite-host relationships. Introduction to ecological parasitology . Springer, Berlin a. a. 1998, ISBN 978-3-540-62859-0 , pp. 23 .
  15. ↑ Physeter macrocephalus in the Red List of Threatened Species of the IUCN 2019. Posted by: BL Taylor, R. Baird, J. Barlow, SM Dawson, J. Ford, JG Mead, G. Notarbartolo di Sciara, P. Wade, RL Pitman, 2008. Retrieved March 7, 2020.