Summary
Placentonema gigantissima is a giant nematode that parasitizes the placenta of the sperm whale. With a length of 8.4 metres (28 ft) and a diameter of 2.5 centimetres (0.98 in), it is potentially the largest nematode worm ever described, inhabiting the largest mammals of the world.[1] It was discovered in the 1950s around the Kuril Islands.[2]
| Placentonema gigantissima | |
|---|---|
| |
| Placentonema gigantissima in the placenta of a sperm whale (Physeter macrocephalus) | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Nematoda |
| Class: | Chromadorea |
| Order: | Rhabditida |
| Family: | Tetrameridae |
| Genus: | Placentonema |
| Species: | P. gigantissima
|
| Binomial name | |
| Placentonema gigantissima (Gubanov, 1951)
| |
Taxonomy edit
Placentonema gigantissima was described in 1951 by Russian parasitologist and helminthologist Nikolai Mikhailovich Gubanov.[2]
Originally described from the family Crassicaudidae,[2] it is now classified in the subfamily Crassicaudinae of the roundworm family, Tetrameridae.
It is a monotypic genus that differs from the only other genus in the subfamily, Crassicauda, by its "caudal alae, stub-like papillae and multiple uterus branching into 32 uteri".[2]
Description edit
Body very long, cylindrical, tapering at the ends, with a transparent cuticle.[2] Oral orifice oval shaped with two simple lateral lips, esophagus with two parts, one muscular and glandular.[2]
Males up to 3.75 m long and 9 mm wide; females up to 8.4 m long and 2.5 cm wide, with up to 32 ovaries.[2][1] Mature eggs oval, 0.05 mm long by 0.03 mm wide, and the young inside the eggs are completely formed.[2]
Life cycle edit
Placentonema gigantissima develops its parasitic nature by utilizing nutrients found in the endometrium of female sperm whales and forming as spiriud (small, embroyonated) eggs.[3]
It can parasitize not only the placenta, but also the uterus, reproductive tract, mammary glands, or subdermis of the sperm whale.[4] It is commonly found in pregnant sperm whales.[5]
Much of the life cycle of P. gigantissima is unknown.[5]
Distribution edit
P. gigantissima is found inside female sperm whales that inhabit lower latitudes of the southern hemisphere.[6]
External links edit
Placentonema gigantissima discussed on RNZ Critter of the Week, 24 November 2023
References edit
- ^ a b Jairajpuri, Shamim (2005-01-01). "Parasite diversity with specific reference to nematodes". Journal of Parasitic Diseases. 29 (2): 81–84.
- ^ a b c d e f g h Gubanov, Nikolai Mikhailovich (21 April 1951). "Гигантская нематода из плаценты китообразных Placentonema gigantissima nov. gen., nov. sp" [Giant nematoda from the placenta of Cetacea; Placentonema gigantissima nov. gen., nov. sp] (PDF). Doklady Akademii Nauk SSSR (in Russian). 77 (6): 1123–1125. PMID 14822893. Archived from the original (PDF) on 15 December 2013.
- ^ Juan-Sallés, Carles; Garner, Michael M. (2019). "67 - Avian Spirurids". Fowler's Zoo and Wild Animal Medicine Current Therapy. 9: 471. doi:10.1016/B978-0-323-55228-8.00067-9. ISBN 9780323552288. S2CID 239100923.
- ^ Hermosilla, Carlos; Hirzmann, J.; Silva, L. M. R.; Brotons, J. M.; Cerdà, M.; Prenger-Berninghoff, E.; Ewers, C.; Taubert, A. (2018). "Occurrence of anthropozoonotic parasitic infections and faecal microbes in free-ranging sperm whales (Physeter macrocephalus) from the Mediterranean Sea". Parasitology Research. 117 (8): 2531–2541. doi:10.1007/s00436-018-5942-3. ISSN 0932-0113.
- ^ a b Dailey, Murray D. (1985-01-01), "Diseases of Mammalia: Cetacea", Diseases of Marine Animals. Vol. 4 part 2, ed. Otto Kinne, pp. 805–848, retrieved 2024-01-09
- ^ Dailey, Murray D.; Vogelbein, Wolfgang K. (1991-01-01). "Parasite fauna of 3 species of Antarctic whales with reference to their use as potential stock indicators". Fishery Bulletin. 89 (3): 355–365.