Nematomorpha

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Nematomorpha
Temporal range: Cenomanian–Recent Possible
Atdabanian
Record
Paragordius tricuspidatus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Subkingdom: Eumetazoa
Clade: ParaHoxozoa
Clade: Bilateria
Clade: Nephrozoa
(unranked): Protostomia
Superphylum: Ecdysozoa
Clade: Nematoida
Phylum: Nematomorpha
Vejdovsky
, 1886
Orders and families
  • Gordioidea Rauther, 1930
    • Chordodidae May, 1919
    • Gordiidae May, 1919
  • Nectonematoidea
    Rauther, 1930
    • Nectonemidae Ward, 1892

Nematomorpha (sometimes called Gordiacea, and commonly known as horsehair worms, hairsnakes,

Gordian knot. This relates to the fact that nematomorphs often coil themselves in tight balls that resemble knots.[7]

Description and biology

Nematomorphs possess an external

nerve ring near the anterior end of the animal, and a ventral nerve cord running along the body.[8]

Reproductively, they have

haemocoel and absorb nutrients directly through their skin. Development into the adult form takes weeks or months, and the larva moults several times as it grows in size.[8]

The adults are mostly free-living in freshwater or marine environments, and males and females aggregate into tight balls (Gordian knots) during mating.[9][10]

Spinochordodes tellinii and its Meconema host

In

crickets as their hosts, the infection acts on the infected host's brain.[11] This causes the host insect to seek water and drown itself, thus returning the nematomorph to water.[9] P. tricuspidatus is also remarkably able to survive the predation of their host, being able to wiggle out of the predator that has eaten the host.[12] The nematomorpha parasite affects host Hierodula patellifera's light-interpreting organs so the host is attracted to horizontally polarized light. Thus the host goes into water and the parasite's lifecycle completes.[13] Many of the genes the parasites use for manipulating their host have been acquired through horizontal gene transfer from the host genome.[14]

There are a few cases of accidental parasitism in vertebrate hosts, including dogs[15] and humans. Several cases involving Parachordodes, Paragordius, or Gordius have been recorded in human hosts in Japan and China.[16][17]

Community ecology

riparian ecosystem showed that nematomorphs can cause orthopterans to become 20 times more likely to enter water than non-infected orthopterans; these orthopterans constituted up to 60% of the annual energy intake for the Kirikuchi char. Absence of nematomorphs from riparian communities can thus lead to char predating more heavily on other aquatic invertebrates, potentially causing more widespread physiological effects.[18]

Taxonomy

See also:
List of bilaterial animal orders

Nematomorphs can be confused with nematodes, particularly mermithid worms. Unlike nematomorphs, mermithids do not have a terminal cloaca. Male mermithids have one or two spicules just before the end apart from having a thinner, smoother cuticle, without areoles and a paler brown colour.[19]

The phylum is placed along with the Ecdysozoa clade of moulting organisms that include the Arthropoda. Their closest relatives are the nematodes. The two phyla make up the group Nematoida in the clade Cycloneuralia. During the larval stage, the animals show a resemblance to adult kinorhyncha and some species of Loricifera and Priapulida, all members of the group Scalidophora.[20] The earliest Nematomorph could be Maotianshania, from the Lower Cambrian; this organism is, however, very different from extant species;[21] fossilized worms resembling the modern forms have been reported from mid Cretaceous Burmese amber dated to 100 million years ago.[22]

Relationships within the phylum are still somewhat unclear, but two classes are recognised. The five marine species of nematomorph are contained in

blastocoelom and singular gonads
.

The approximately 320 remaining species are distributed between two families,

Gordioida. Gordioidean adults are free-living in freshwater or semiterrestrial habitats and larvae parasitise insects, primarily orthopterans.[23] Unlike nectonematiodeans, gordioideans lack lateral rows of setae, have a single, ventral epidermal cord and their blastocoels are filled with mesenchyme
in young animals but become spacious in older individuals.

References

Citations

  1. ^ Heston, Joshua. "Horse Hair Snake". State of the Ozarks. Retrieved 1 January 2021.
  2. ^ Troxell, W.H. (30 January 1903). "Erroneous Beliefs" (PDF). Emmitsburg Chronicle. No. 37. Archived (PDF) from the original on 2021-05-09. Retrieved 1 January 2021.
  3. ^ Ningewance, Pat (8–10 August 1996). "Naasaab Izhi-anishinaabebii'igeng conference report: a conference to find a common Anishinaabemowin writing system" (PDF). Toronto, Ontario: Literacy Ontario. p. 27. Archived (PDF) from the original on 2020-10-22. Girls, don't swim without pants or a hairsnake will enter you.
  4. PMID 16182867. {{cite book}}: |journal= ignored (help)CS1 maint: multiple names: authors list (link
    )
  5. doi:10.11646/zootaxa.3148.1.3. Archived
    (PDF) from the original on 2022-10-10.
  6. S2CID 37985613
    .
  7. Greenwood Press
    .
  8. ^
    ISBN 978-0-03-056747-6
    .
  9. ^
    S2CID 86278524. Archived from the original
    (PDF) on 2015-09-24. — according to Thomas et al., the "infected insects may first display an erratic behaviour which brings them sooner or later close to a stream and then a behavioural change that makes them enter the water", rather than seeking out water over long distances.
  10. PMID 21708759
    .
  11. PMID 12705936
    .
  12. S2CID 7777607
    .
  13. ^ "Parasites manipulate praying mantis's polarized-light perception, causing it to jump into water". phys.org. Retrieved 2021-07-04.
  14. ^ This Parasitic Worm ‘Steals’ Genes From Its Unsuspecting Host
  15. PMID 26797439
    .
  16. PMID 22949758
    .
  17. PMID 3430914
    .
  18. S2CID 20274754
    .
  19. ^ Malcolm S. Bryant, Robert D. Adlard & Lester R.G. Cannon 2006. Gordian Worms: Factsheet. Queensland Museum. "Archived copy" (PDF). Archived from the original (PDF) on 2008-07-22. Retrieved 2008-03-10.{{cite web}}: CS1 maint: archived copy as title (link)
  20. ^ Nematomorpha – Bumblebees
  21. ^ Sun, W.; Hou, X. (1987). "Early Cambrian worms from Chengjiang, Yunnan, China: Maotianshania gen. nov" (Paywall). Acta Palaeontologica Sinica. 26 (3): 299–305.
  22. PMID 16737709
    .
  23. ^ a b c Pechenik, 'Biology of the Invertebrates, 2010, pg 457.
  24. ^ "Gordioidea". Integrated Taxonomic Information System.

General and cited references

  • Pechenik, Jan A. (2010). "Four Phyla of Likely Nematode Relatives". Biology of the Invertebrates (6th International ed.). Singapore: Mc-Graw Hill Education (Asia). pp. 452–457.
    ISBN 978-0-07-127041-0
    .

Further reading

External links

Wikisource has the text of the 1911 Encyclopædia Britannica article "Nematomorpha".
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