Nematomorpha are a phylum of parasitoid animals superficially similar to nematode worms in morphology, hence the name. Most species range in size from 50 to 100 millimetres long, reaching 2 metres in extreme cases, 1 to 3 millimetres in diameter. Horsehair worms can be discovered in damp areas, such as watering troughs, swimming pools, streams and cisterns; the adult worms are free-living, but the larvae are parasitic on arthropods, such as beetles, mantids and crustaceans. About 351 freshwater species are known and a conservative estimate suggests that there may be about 2000 freshwater species worldwide; the name "Gordian" stems from the legendary Gordian knot. This relates to the fact that nematomorphs tie themselves in knots. Nematomorphs possess an external cuticle without cilia. Internally, they have only longitudinal muscle and a non-functional gut, with no excretory, respiratory or circulatory systems; the nervous system consists of a nerve ring near the anterior end of the animal, a ventral nerve cord running along the body.
Reproductively, they have two distinct sexes, with the internal fertilization of eggs that are laid in gelatinous strings. Adults have cylindrical gonads; the larvae have rings of cuticular hooks and terminal stylets that are believed to be used to enter the hosts. Once inside the host, the larvae live inside the haemocoel and absorb nutrients directly through their skin. Development into the adult form takes weeks or months, the larva moults several times as it grows in size; the adults are free-living in freshwater or marine environments, males and females aggregate into tight balls during mating. In Spinochordodes tellinii and Paragordius tricuspidatus, which have grasshoppers and crickets as their hosts, the infection acts on the infected host's brain; this causes the host insect to drown itself, thus returning the nematomorph to water. P. tricuspidatus is remarkably able to survive the predation of their host, being able to wiggle out of the predator that has eaten the host. There are a few cases including dogs and humans.
Several cases involving Parachordodes, Paragordius, or Gordius have been recorded in human hosts in Japan and China. Nematomorphs can be confused with nematodes 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; 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; the earliest Nematomorph could be Maotianshania, from the Lower Cambrian. Relationships within the phylum are still somewhat unclear; the five marine species of nematomorph are contained in Nectonematoida. Adults are planktonic and the larvae parasitise decapod crustaceans crabs.
They are characterized by a double row of natotory setae along each side of the body and ventral longitudinal epidermal cords, a spacious and fluid-filled blastocoelom and singular gonads. The 320 remaining species are distributed between two families, comprising seven genera, within order Gordioida. Gordioidean adults are free-living in freshwater or semiterrestrial habitats and larvae parasitise insects orthopterans. 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. Pechenik, Jan A.. "Four Phyla of Likely Nematode Relatives". Biology of the Invertebrates. Singapore: Mc-Graw Hill Education. Pp. 452–457. ISBN 978-0-07-127041-0. Baker GL, Capinera JL. "Nematodes and nematomorphs as control agents of grasshoppers and locusts". Memoirs of the Entomological Society of Canada. 171: 157–211. Doi:10.4039/entm129171157-1. Hanelt B, Thomas F, Schmidt-Rhaesa A.
Biology of the phylum Nematomorpha. Advances in Parasitology. 59. Pp. 244–305. Doi:10.1016/S0065-308X59004-3. ISBN 9780120317592. PMID 16182867. Poinar GO Jr. "Nematoda and Nematomorpha". In Thorp JH, Covich AP. Ecology and Classification of North American Freshwater Invertebrates. San Diego, CA: Academic Press. Pp. 249–283. Thorne G. "The hairworm, Gordius robustus Leidy, as a parasite of the Mormon cricket, Anabrus simplex Haldeman". Journal of the Washington Academy of Science. 30: 219–231. Hairworm Biodiversity Survey. Capinera, J. L. Horsehair Worms, Gordian Worms, Gordius spp.. University of Florida IFAS. Published 1999, revised 2005. Nematomorph worm – Behavior modification of cricket by nematomorph worm. YouTube. Gordian worms discussed on RNZ Critter of the Week, 6 November 2015
The Serra dos Ancares is a mountain range of the Galician Massif in north-west Spain, extending in a south-westerly direction from the western end of the Cantabrian Mountains in Asturias. The range forms the boundary between León; the highest point of the range is the Cuiña Peak at 1,987 metres. Other notable peaks are Miravalles; the smaller Serra do. The main trees in the range are willow and European alder close to water courses, as well as chestnut, common hazel and common holly. Above 1,600 metres there is brushland with tree juniper; this area of Spain contains many isolated rural communities that were cut off from the outside world until roads were built in the mid 20th century. The most significant element of the whole architecture of the area is the palloza or casa teito, stone buildings of ancient origin, with a circular or elliptical plan. Sierra de los Ancares is the name of a Site of Community Importance in the province of León. Os Ancares Lucenses y Montes de Cervantes, Navia y Becerrea was declared a UNESCO Biosphere Reserve in 2006.
Rivière Qui Barre is a hamlet in central Alberta, within Sturgeon County. It is located 1 kilometre west of Highway 44 22 kilometres northwest of Edmonton's city limits, it was founded in 1885 by French-speaking settlers, adding a post office in 1895. The name is the French translation of the Cree name of the nearby river; as a designated place in the 2016 Census of Population conducted by Statistics Canada, Rivière Qui Barre recorded 15 people living in four of the hamlet's six total private dwellings. With a land area of 0.58 km2, it had a population density of 25.9/km2 in 2016. The population of Rivière Qui Barre has declined in recent years. In Sturgeon County's 2008 municipal census, the population was 100, which had declined to 56 by the 2011 Census of Population. Since 2008, the total change has been -85%. While the hamlet of Rivière Qui Barre has only 15 people, it is a recreation and education center for this part of Sturgeon County; the Rivière Qui Barre Arena provides an indoor ice hockey venue for the area.
In January 2017, the Government of Canada announced that the arena's operator, the Rivière Qui Barre Agricultural Society, would receive a $200,000 grant for upgrades as part of a series of infrastructure projects celebrating the 150th anniversary of Canada becoming a nation. In March 2017, Sturgeon County added a further $100,000 grant for the renovations; the Sturgeon School Division operates Camilla School in Rivière Qui Barre, serving 470 elementary and junior high students from the region in the 2016–17 school year. In March 2017, the Alberta Minister of Education announced that a new Camilla School will be built by 2021, replacing the structure built in 1954. List of communities in Alberta List of hamlets in Alberta