Coxal gland

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Coxal gland and its components Coxal-gland.jpg
Coxal gland and its components

The coxal gland is a gland found in some arthropods, for collecting and excreting urine. They are found in all arachnids (with the exception of some Acari), and in other chelicerates, such as horseshoe crabs. [1] The coxal gland is thought to be homologous with the antennal gland of crustaceans. The gland consists of an end sac (saccule), a long duct (labyrinth) and a terminal bladder (reservoir). [2] There is generally only one pair (two in some spiders), and they open on the coxae of the walking legs [1] or at the base of the second antennae in the case of the crustacean antennal gland. [3] :70–71 The coxal secretion of adult female ticks of Ornithodoros erraticus contains a sex pheromone. [4] In Spiders, the coxal glands should not be confused with segmentary organs, a whole set of even and symmetrical exocrine structures, apparently metamerized, located in the prosoma of spiders on the base of the appendages, the most important being the retrognathocoxal glands. They were discovered microscopically and named by André Lopez for the first time in Metepeira and later on in other genera (1978,1983,1984)(external link "archentoflor")

Contents

Excretory system

The excretory system of the prawn lacks a true kidney. The following parts are found in its excretory system: [3]

Communication

In invertebrates with coxal glands, many forms of communication are conveyed via chemicals in the urine. Several studies have shown that in crayfish, these chemicals convey information such as reproductive capability, the identity of individual crayfish, as well as their aggression levels and hierarchical status. [5] For example, when two male crayfish meet, they will engage in combat. Combat determines which individual is "dominant" or "submissive" in the hierarchy. These encounters affect their aggression levels, regulated by serotonin, and thus changes the chemical composition of their urine . The chemical changes undergone will mediate further encounters, as they will offer crayfish a certain level of "familiarity" with each other. The chemicals in their urine communicate their rank to other crayfish and while the intensity of the encounter remains the same, the length of the encounter will be much shorter. [6]

Communication interference

Foreign chemicals introduced into the ecosystem have the potential to interfere with the arthropod's chemical receptors. Insecticide run-off from agricultural applications has been shown to inhibit communication in crayfish. Neonicotinoids are widely used systemic insecticides that act as a neurotoxin to most arthropods that are water soluble and frequently make it into various waterways. [7] Neonicotinoids bind to nicotinic acetylcholine receptors (nAChR), which kills insects by overstimulating them. nAChRs can be found in the interneurons of the brain, neuromuscular junctions, and the olfactory bulb. [8] Neonicotinoids binding to these receptors prevents the chemicals involved in communication from binding to their proper receptors. As a result, crayfish exposed to these insecticides at sublethal doses lose their ability to detect certain cues. Crayfish will fail to recognize individuals that they have had previous encounters with, as well as their hierarchical status. Crayfish also will fail to find food, and lab experiments show that they display no preference for environments with or without food. [8]

References

  1. 1 2 Colin Little (1983). "Chelicerates". The Colonisation of Land: Origins and Adaptations of Terrestrial Animals. Cambridge University Press. pp. 106–126. ISBN   978-0-521-25218-8.
  2. H. S. Bhamrah & Kavita Juneja (2002). "Scorpions". An Introduction to Arthropoda (2nd ed.). Anmol Publications. pp. 317–342. ISBN   978-81-261-0673-8.
  3. 1 2 Kibenge, Frederick S. B.; Strange, Richard J. (2021-01-01). "Chapter 1 - Introduction to the anatomy and physiology of the major aquatic animal species in aquaculture". In Kibenge, Frederick S. B.; Baldisserotto, Bernardo; Chong, Roger Sie-Maen (eds.). Aquaculture Pharmacology. Academic Press. pp. 1–111. doi:10.1016/B978-0-12-821339-1.00001-5. ISBN   978-0-12-821339-1.
  4. Schlein, Y.; Gunders, A. E. (1981). "Pheromone of Ornithodoros spp. (Argasidae) in the coxal fluid of female ticks" . Parasitology. 82 (3): 467–471. doi:10.1017/S0031182000066993. S2CID   85691239.
  5. Kubec, Jan; Kouba, Antonín; Buřič, Miloš (2019-01-01). "Communication, behaviour, and decision making in crayfish: A review" . Zoologischer Anzeiger. 278: 28–37. Bibcode:2019ZooAn.278...28K. doi:10.1016/j.jcz.2018.10.009. ISSN   0044-5231. S2CID   92105429.
  6. Huber, Robert; Schneider, Rebecca A. Zulandt; Moore, Paul (2001-01-01). "Individual and Status Recognition in the Crayfish, Orconectes Rusticus: The Effects of Urine Release on Fight Dynamics" . Behaviour. 138 (2): 137–153. doi:10.1163/15685390151074348. ISSN   0005-7959.
  7. Goulson, Dave (2013-06-13). "REVIEW: An overview of the environmental risks posed by neonicotinoid insecticides" . Journal of Applied Ecology. 50 (4): 977–987. Bibcode:2013JApEc..50..977G. doi:10.1111/1365-2664.12111. ISSN   0021-8901. S2CID   267975.
  8. 1 2 Scholl, Lee E.; Sultana, Tamanna; Metcalfe, Chris; Dew, William A. (2022-06-01). "Clothianidin interferes with recognition of a previous encounter in rusty crayfish (Faxonius rusticus) due to a chemosensory impairment" . Chemosphere. 296 133960. Bibcode:2022Chmsp.29633960S. doi:10.1016/j.chemosphere.2022.133960. ISSN   0045-6535. PMID   35167832. S2CID   246810470.