Diving bell spider

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Diving bell spider
Argyroneta aquatica Paar.jpg
Female (on left) and male
Scientific classification edit
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Dictynidae
Genus: Argyroneta
Latreille, 1804
Species:
A. aquatica
Binomial name
Argyroneta aquatica
(Clerck, 1758)
Synonyms[1]

Araneus aquaticus
Aranea aquatica
Aranea urinatoria
Aranea amphibia
Clubiona fallax

The diving bell spider or water spider (Argyroneta aquatica) is the only species of spider known to live almost entirely under water. It is the only member of the genus Argyroneta. When out of the water, the spider ranges in colour from mid to dark brown, although the hairs on the abdomen give it a dark grey, velvet-like appearance.[2] It is native to freshwater habitats in Europe and Asia.[3]

Uniqueness of aquatic behavior[edit]

Although prey usually is consumed underwater in the diving bell, it is occasionally brought to the surface

A. aquatica is the only known species of spider that spends almost all its life underwater, including resting, catching and eating prey, mating, egg laying and overwintering. It only briefly surfaces to replenish its oxygen supply and occasionally will bring prey to the surface.[4][5][6][7]

There are several other spiders that are semiaquatic, either periodically living underwater or willing to dive. For example, certain Desis species spend the high tide in an air-filled underwater retreat made from silk and forage on land in the intertidal zone during low tide.[5][8][9] Some spiders living in periodically flooded habitats can survive for an extended period of time underwater by entering a coma-like state, up to 16–36 hours in Arctosa fulvolineata.[10] Numerous species, including some Ancylometes, Dolomedes, Megadolomedes, Pardosa, Pirata, Thalassius and others, live above water at the surface, but may actively submerge for a prolonged period of time, are strong swimmers and will catch underwater prey.[4][5][11] Several of these, as well as a few others, may dive into water to avoid larger predators.[4][12]

Distribution and habitat[edit]

A. aquatica is found in clean freshwater habitats with aquatic vegetation, such as lakes, ponds, canals, marshes and slow-moving streams.[6][13] It ranges through much of mainland Europe (no records from Portugal, Greece and Albania), the British Isles and northern Asia (Turkey, Caucasus, Russia, Iran, Central Asia, China, Korea and Japan) up to latitude 62°N.[3][14] Most of the range is inhabited by the nominate subspecies, but Japan has its own subspecies, the very similar A. a. japonica.[2][15]

Ecology[edit]

As with other spiders it breathes air; when submerged in water, an air bubble is trapped by a dense layer of hydrophobic hairs on its abdomen and legs,[3] giving the abdomen a silvery appearance. The spider lives for about two years in captivity.[3]

A. aquatica is able to remain submerged for prolonged periods of time due to the silk-based structure it constructs in order to retain an oxygen supply, named after the diving bell structure it resembles. The species range in size, although the size of females may be limited as they put more energy into building and maintaining their larger bells.[3] Males are more active and on average almost 30% larger than females,[3] measuring 10–15 mm (0.39–0.59 in) in head-and-body length compared to 8–12 mm (0.31–0.47 in).[2] This size differential favoring males is unusual for spiders, where sexual dimorphism is usually in favour of larger females. Theories suggest that the male's more active hunting style requires greater strength to overcome water resistance and counteract the buoyancy of their mobile air supplies. This larger body size is also associated with longer front legs, shown to affect diving ability and giving the males superiority in diving over the more sessile females.[3]

The spiders prey on aquatic insects and crustaceans such as mosquito larvae and Daphnia.[16] The spiders themselves fall prey to frogs and fish.[17]

Diving bell[edit]

The appearance of the diving bell gave rise to the genus name Argyroneta, from the Greek "argyros" (ἄργυρος), meaning "silver", and "neta", a neologism (perhaps for *νητής) derived from the verb "neo" (νέω) "spin", intended to mean "spinner of silver".[18] Both sexes build diving bell webs which are used for digesting prey, although only the female's larger bell is used for mating and raising offspring. Females spend most of their time within their bells, darting out to catch prey animals that touch the bell or the silk threads that anchor it and occasionally surfacing to replenish the air within the web. The bells built by males are typically smaller than females and are replenished less often. It is thought that prior to mating, the male constructs a diving bell adjacent to the female's then spins a tunnel from his bell, breaking into hers to gain entrance.[17] Mating takes place in the female's bell.[19] The female spider then constructs an egg sac within her bell, laying between 30 and 70 eggs.[17] Where this species moults is less clear, with some sources stating that it occurs below water in the diving bell[7] and others that it occurs out of water.[6]

Diving bells are irregularly constructed sheets of silk and an unknown protein-based hydrogel[20] which is spun between submerged water plants then inflated with air brought down from the surface by the builder. Studies have considered gas diffusion between the diving bell and the spiders’ aquatic environment. The silk is waterproof but allows gas exchange with the surrounding water. There is net diffusion of oxygen into the bell and net diffusion of carbon dioxide out. This process is driven by differences in partial pressure. The production of carbon dioxide and use of oxygen by the spider maintains the concentration gradient, required for diffusion. However, there is net diffusion of nitrogen out of the bell, resulting in a gradually shrinking air bubble which must be regularly replenished by the spider.[16]

Larger spiders are able to produce larger bubbles which have a consequently higher oxygen conductance, but all spiders of this species are able to enlarge their bells in response to increased oxygen demands in low aquatic P(O2) environments. These spiders voluntarily tolerate internal conditions of low oxygen, enlarging their bells with air when the P(O2) drops below 1 kPa; this replenishment process may not need to occur for several days, in some cases.[16] This system has been referred to as "the water spider's aqua-lung of air bubbles", though an aqua-lung lacks gas exchange with the surroundings;[21] this system is more properly regarded as an inorganic form of gill.

Bite[edit]

Their bite is often described as being quite painful to humans, and causing localised inflammation, vomiting and slight feverishness that disappears within a few days.[22][23] However, solid evidence is lacking,[24] with information being based on old unverified reports since recent confirmed reports are lacking,[14][25] leading some sources to refer to its bite as reputedly painful.[2]

References[edit]

  1. ^ Norman I. Platnick (March 27, 2010). "Fam. Cybaeidae Banks, 1892d: 95". The World Spider Catalog, Version 11.0. American Museum of Natural History. Retrieved August 30, 2010.
  2. ^ a b c d "Argyroneta aquatica (Clerck 1758) (Water spider)". danmarks-edderkopper.dk. Retrieved 14 September 2015.
  3. ^ a b c d e f g Schütz, D.; Taborsky, M. (2003). "Adaptations to an aquatic life may be responsible for the reversed sexual size dimorphism in the water spider, Argyroneta aquatica" (PDF). Evolutionary Ecology Research. 5 (1): 105–117. Archived from the original (PDF) on 2008-12-16.
  4. ^ a b c Thorp, J.H.; D.C. Rogers, eds. (2015). Thorp and Covich's Freshwater Invertebrates: Ecology and General Biology. 1 (4 ed.). Elsevier. pp. 602–608. ISBN 978-0-12-385026-3.
  5. ^ a b c Hillyard, P.D. (2007). The Private Life of Spiders. New Holland. pp. 41–43. ISBN 978-0-69115-003-1.
  6. ^ a b c "Argyroneta aquatica (Araneae)". British Arachnological Society. Retrieved 12 April 2018.
  7. ^ a b Schütz, D.; M. Taborsky; T. Drapela (2007). "Air bells of water spiders are an extended phenotype modified in response to gas composition". J Exp Zool A Ecol Genet Physiol. 307 (10): 549–555. doi:10.1002/jez.410.
  8. ^ Baehr, B.C.; Raven, R.; Harms, D. (2017). ""High Tide or Low Tide": Desis bobmarleyi sp. n., a new spider from coral reefs in Australia's Sunshine State and its relative from Sāmoa (Araneae, Desidae, Desis)". Evolutionary Systematics. 1: 111–120. doi:10.3897/evolsyst.1.15735.
  9. ^ "Desis sp. Marine Spiders". arachne.org.au. Retrieved 12 April 2018.
  10. ^ Pétillon, J.; W. Montaigne; D. Renault (2009). "Hypoxic coma as a strategy to survive inundation in a salt-marsh inhabiting spider". Biol. Lett. 5 (4). doi:10.1098/rsbl.2009.0127. PMC 2781913.
  11. ^ Nyffeler, M.; Pusey, B.J. (2014). "Fish Predation by Semi-Aquatic Spiders: A Global Pattern". PLoS ONE. 9 (6): e99459. doi:10.1371/journal.pone.0099459.
  12. ^ Hénaut, Y.; Corbara, B.; Azémar, F.; Céréghino, R.; Dézerald, O.; Dejean, A. (2018). "An arboreal spider protects its offspring by diving into the water of tank bromeliads". Comptes Rendus Biologies. 341 (3): 196–199. doi:10.1016/j.crvi.2018.02.002.
  13. ^ Filoramo, R. (2012). "Argyroneta aquatica". Animal Diversity Web. Retrieved 12 April 2018.
  14. ^ a b "Argyroneta aquatica (Clerck, 1757)". Araneae – Spiders of Europe. 2013. Retrieved 12 April 2018.
  15. ^ Ono, H. (2002). "New and Remarkable Spiders of the Families Liphistiidae, Argyronetidae, Pisauridae, Theridiidae and Araneidae (Arachnida) from Japan". Bulletin of the National Museum of Nature and Science Tokyo (A). 28 (1): 51–60. doi:10.1016/j.crvi.2018.02.002.
  16. ^ a b c Seymour, R. S.; Hetz, S. K. (2011). "The diving bell and the spider: the physical gill of Argyroneta aquatica". J. Exp. Biol.: 2175–2181.
  17. ^ a b c Chandramita Bora. "Water Spider".
  18. ^ Thorell, Tord (1869). On European Spiders. Uppsala, Sweden: Royal Society of Upsala. p. 137. Retrieved January 10, 2017.
  19. ^ Schütz, Dolores; Taborsky, Michael (2005). "Mate choice and sexual conflict in the size dimorphic water spider, Argyroneta aquatica (Araneae, Argyronatidae)" (PDF). Journal of Arachnology. 33.
  20. ^ Neumann, Dietrich; Kureck, Armin (2013). "Composite structure of silken threads and a protinaceous hydrogel which form the diving bell wall of the water spider Argyroneta aquatica". SpringerPlus. 2 (223). Retrieved 7 August 2015.
  21. ^ Flynn, M. R.; Bush, John W. M. (2008). "Underwater breathing: the mechanics of plastron respiration". J. Fluid Mech. Cambridge University Press. 608: 275–296. doi:10.1017/S0022112008002048.
  22. ^ Ross Piper (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
  23. ^ Foelix, R.F. (2011). Biology of Spiders (3 ed.). Oxford University Press. p. 57. ISBN 978-0-19-973482-5.
  24. ^ White, J.; J. Meier, eds. (2008). Handbook of Clinical Toxicology of Animal Venoms and Poisons. Informa Healthcare. ISBN 978-0-8493-4489-3.
  25. ^ Nentwig, W.; M. Gnädinger; F.J, Ceschi (2013). "A two year study of verified spider bites in Switzerland and a review of the European spider bite literature". Toxicon. 73: 104–110. doi:10.1016/j.toxicon.2013.07.010.

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