What Animals Are in the Arachnid Family When I See You Again Lyrics

Form of arthropods

Arachnids Temporal range: 435–0 Ma PreꞒ Ꞓ O S D C P T J Grand Pg N Early Silurian – present
Clockwise from top left: Brachypelma hamorii, a Mexican redknee tarantula; Hottentotta tamulus, an Indian cherry scorpion; Aceria anthocoptes, a russet mite; Gluvia dorsalis, a camel spider; Hadrobunus grandis, a harvestman; Ixodes ricinus, a castor edible bean tick
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Form:	Arachnida Lamarck, 1801
Orders
Ricinulei – hooded tickspiders Opiliones – harvestmen Solifugae – camel spiders Acariformes mites Parasitiformes mites and ticks Pseudoscorpiones – pseudoscorpions Scorpiones – scorpions †Phalangiotarbi (extinct) †Trigonotarbida (extinct) †Uraraneida (extinct) Araneae – spiders †Haptopoda (extinct) Amblypygi – whip spiders Schizomida – short-tailed whipscorpions Palpigradi – micro-whipscorpions Thelyphonida – vinegaroons ?Xiphosura – horseshoe crabs

Arachnida () is a grade of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegaroons.^[1]

Almost all adult arachnids have viii legs, although the front pair of legs in some species has converted to a sensory function, while in other species, different appendages tin grow large enough to take on the appearance of extra pairs of legs. The term is derived from the Greek word ἀράχνη (aráchnē, 'spider'), from the myth of the hubristic human weaver Arachne, who was turned into a spider.^[2]

Almost all extant arachnids are terrestrial, living mainly on land. However, some inhabit freshwater environments and, with the exception of the pelagic zone, marine environments too. They comprise over 100,000 named species, of which 47,000 are species of spiders.^[iii]

Morphology [edit]

Bones characteristics of arachnids include four pairs of legs (1) and a torso divided into two tagmata: the cephalothorax (ii) and the abdomen (iii)

Nigh all adult arachnids take eight legs, different adult insects which all take vi legs. Yet, arachnids likewise have ii further pairs of appendages that have get adapted for feeding, defense force, and sensory perception. The first pair, the chelicerae, serve in feeding and defence force. The next pair of appendages, the pedipalps, accept been adapted for feeding, locomotion, and/or reproductive functions. In Solifugae, the palps are quite leg-like, then that these animals appear to have ten legs. The larvae of mites and Ricinulei have only vi legs; a 4th pair usually appears when they moult into nymphs. However, mites are variable: as well as eight, at that place are adult mites with six or even four legs.^[4]

Arachnids are further distinguished from insects by the fact they exercise not accept antennae or wings. Their trunk is organized into 2 tagmata, called the prosoma, or cephalothorax, and the opisthosoma, or abdomen. (Even so, at that place is currently neither fossil nor embryological show that arachnids ever had a carve up thorax-similar division, so the validity of the term cephalothorax, which means a fused cephalon, or head, and thorax, has been questioned. There are besides arguments against use of 'abdomen', as the opisthosoma of many arachnids contains organs atypical of an abdomen, such as a heart and respiratory organs.^[five]) The prosoma, or cephalothorax, is ordinarily covered past a single, unsegmented carapace. The abdomen is segmented in the more primitive forms, but varying degrees of fusion between the segments occur in many groups. It is typically divided into a preabdomen and postabdomen, although this is only clearly visible in scorpions, and in some orders, such equally the Acari, the abdominal sections are completely fused.^[vi] A telson is present in scorpions, where information technology has been modified to a stinger, and in the Schizomida, whip scorpions and Palpigradi.^[7]

Similar all arthropods, arachnids have an exoskeleton, and they also have an internal structure of cartilage-similar tissue, called the endosternite, to which sure muscle groups are fastened. The endosternite is even calcified in some Opiliones.^[8]

Locomotion [edit]

Most arachnids lack extensor muscles in the distal joints of their appendages. Spiders and whipscorpions extend their limbs hydraulically using the pressure of their hemolymph.^[9] Solifuges and some harvestmen extend their knees by the employ of highly elastic thickenings in the joint cuticle.^[9] Scorpions, pseudoscorpions and some harvestmen have evolved muscles that extend two leg joints (the femur-patella and patella-tibia joints) at one time.^{[x] [11]} The equivalent joints of the pedipalps of scorpions though, are extended by elastic recoil.^[12]

Physiology [edit]

There are characteristics that are particularly important for the terrestrial lifestyle of arachnids, such as internal respiratory surfaces in the form of tracheae, or modification of the book gill into a book lung, an internal series of vascular lamellae used for gas exchange with the air.^[13] While the tracheae are oft individual systems of tubes, similar to those in insects, ricinuleids, pseudoscorpions, and some spiders possess sieve tracheae, in which several tubes arise in a bundle from a small chamber connected to the spiracle. This type of tracheal arrangement has most certainly evolved from the volume lungs, and indicates that the tracheae of arachnids are not homologous with those of insects.^[xiv]

Farther adaptations to terrestrial life are appendages modified for more than efficient locomotion on land, internal fertilisation, special sensory organs, and water conservation enhanced by efficient excretory structures as well as a waxy layer covering the cuticle.

The excretory glands of arachnids include up to four pairs of coxal glands along the side of the prosoma, and 1 or two pairs of Malpighian tubules, elimination into the gut. Many arachnids have only ane or the other type of excretory gland, although several exercise have both. The master nitrogenous waste production in arachnids is guanine.^[14]

Arachnid claret is variable in composition, depending on the mode of respiration. Arachnids with an efficient tracheal system exercise non need to transport oxygen in the blood, and may have a reduced circulatory system. In scorpions and some spiders, withal, the blood contains haemocyanin, a copper-based pigment with a similar function to haemoglobin in vertebrates. The heart is located in the forward part of the abdomen, and may or may not be segmented. Some mites accept no heart at all.^[14]

Diet and digestive system [edit]

Arachnids are generally carnivorous, feeding on the pre-digested bodies of insects and other small animals. Simply in the harvestmen and among mites, such as the house dust mite, is their ingestion of solid food particles, and thus exposure to internal parasites,^[xv] although it is not unusual for spiders to eat their own silk. Several groups secrete venom from specialized glands to impale prey or enemies. Several mites and ticks are parasites, some of which are carriers of disease.

Arachnids produce digestive juices in their stomachs, and use their pedipalps and chelicerae to pour them over their dead prey. The digestive juices rapidly turn the prey into a broth of nutrients, which the arachnid sucks into a pre-buccal cavity located immediately in front of the mouth. Behind the mouth is a muscular, sclerotised pharynx, which acts as a pump, sucking the nutrient through the mouth and on into the oesophagus and tum. In some arachnids, the oesophagus as well acts equally an additional pump.

The stomach is tubular in shape, with multiple diverticula extending throughout the body. The tummy and its diverticula both produce digestive enzymes and absorb nutrients from the nutrient. It extends through most of the trunk, and connects to a short sclerotised intestine and anus in the hind part of the belly.^[fourteen]

Senses [edit]

Arachnids accept two kinds of eyes: the lateral and median ocelli. The lateral ocelli evolved from compound eyes and may have a tapetum, which enhances the ability to collect light. With the exception of scorpions, which can have up to five pairs of lateral ocelli, at that place are never more than three pairs present. The median ocelli develop from a transverse fold of the ectoderm. The ancestors of modernistic arachnids probably had both types, but modern ones often lack 1 type or the other.^[15] The cornea of the eye also acts every bit a lens, and is continuous with the cuticle of the body. Beneath this is a transparent vitreous torso, and so the retina and, if present, the tapetum. In most arachnids, the retina probably does not have enough light sensitive cells to let the eyes to form a proper prototype.^[14]

In addition to the eyes, almost all arachnids have ii other types of sensory organs. The near important to most arachnids are the fine sensory hairs that cover the torso and give the animal its sense of touch. These tin can be relatively simple, just many arachnids also possess more complex structures, called trichobothria.

Finally, slit sense organs are slit-like pits covered with a thin membrane. Inside the pit, a pocket-sized hair touches the underside of the membrane, and detects its motility. Slit sense organs are believed to be involved in proprioception, and peradventure also hearing.^[14]

Reproduction [edit]

Arachnids may have i or two gonads, which are located in the belly. The genital opening is commonly located on the underside of the second abdominal segment. In most species, the male person transfers sperm to the female in a package, or spermatophore. Circuitous courtship rituals take evolved in many arachnids to ensure the prophylactic delivery of the sperm to the female.^[14] Members of many orders exhibit sexual dimorphism.^[16]

Arachnids unremarkably lay yolky eggs, which hatch into immatures that resemble adults. Scorpions, however, are either ovoviviparous or viviparous, depending on species, and comport live immature. In most arachnids only the females provide parental care, with harvestmen being 1 of the few exceptions.^{[ commendation needed ]}

Taxonomy and evolution [edit]

Phylogeny [edit]

The phylogenetic relationships amongst the master subdivisions of arthropods have been the subject field of considerable research and dispute for many years. A consensus emerged from nearly 2010 onwards, based on both morphological and molecular evidence. Extant (living) arthropods are a monophyletic group and are divided into 3 master clades: chelicerates (including arachnids), pancrustaceans (the paraphyletic crustaceans plus insects and their allies), and myriapods (centipedes, millipedes and allies).^{[17] [xviii] [19] [xx] [21]} The iii groups are related as shown in the cladogram below.^[19] Including fossil taxa does not fundamentally change this view, although it introduces some additional basal groups.^[22]

The extant chelicerates comprise two marine groups: body of water spiders and horseshoe crabs, and the terrestrial arachnids. These have been thought to be related every bit shown below.^{[18] [21]} (Pycnogonida (sea spiders) may exist excluded from the chelicerates, which are and then identified as the group labelled "Euchelicerata".^[23]) A 2019 analysis nests Xiphosura securely inside Arachnida.^[24]

Discovering relationships within the arachnids has proven hard equally of March 2016^[update], with successive studies producing different results. A written report in 2014, based on the largest set of molecular data to date, concluded that at that place were systematic conflicts in the phylogenetic data, particularly affecting the orders Acariformes, Parasitiformes and Pseudoscorpiones, which have had much faster evolutionary rates. Analyses of the data using sets of genes with different evolutionary rates produced mutually incompatible phylogenetic trees. The authors favoured relationships shown by more than slowly evolving genes, which demonstrated the monophyly of Chelicerata, Euchelicerata and Arachnida, as well as of some clades within the arachnids. The diagram below summarizes their conclusions, based largely on the 200 nigh slowly evolving genes; dashed lines correspond uncertain placements.^[21]

Tetrapulmonata, here consisting of Araneae, Amblypygi and Thelyphonida (Schizomida was non included in the study), received strong back up. The addition of Scorpiones to produce a clade called Arachnopulmonata was also well supported. Pseudoscorpiones may also belong hither, possibly every bit the sis of Scorpiones. Somewhat unexpectedly, there was support for a clade comprising Opiliones, Ricinulei and Solifugae, a combination not found in about other studies.^[21] In early on 2019, a molecular phylogenetic analysis placed the horseshoe crabs, Xiphosura, as the sister group to Ricinulei. It also grouped pseudoscorpions with mites and ticks, which the authors considered may be due to long branch attraction.^[24]

Morphological analyses including fossils tend to recover the Tetrapulmonata, including the extinct group the Haptopoda,^{[25] [26] [27] [28] [29]} but recover other ordinal relationships with low support.

Fossil history [edit]

The Uraraneida are an extinct order of spider-similar arachnids from the Devonian and Permian.^[30]

A fossil arachnid in 100 million year old (mya) bister from Myanmar, Chimerarachne yingi, has spinnerets (to produce silk); it also has a tail, like the Palaeozoic Uraraneida, some 200 1000000 years after other known fossils with tails. The fossil resembles the nigh primitive living spiders, the mesotheles.^{[31] [25]}

Taxonomy [edit]

The subdivisions of the arachnids are unremarkably treated as orders. Historically, mites and ticks were treated as a unmarried society, Acari. However, molecular phylogenetic studies suggest that the two groups exercise non form a unmarried clade, with morphological similarities being due to convergence. They are now usually treated as two split taxa – Acariformes, mites, and Parasitiformes, ticks – which may be ranked as orders or superorders. The arachnid subdivisions are listed below alphabetically; numbers of species are approximate.

• Acariformes – mites (32,000 species)
• Amblypygi – "blunt rump" tail-less whip scorpions with front legs modified into whip-like sensory structures as long as 25 cm or more (153 species)
• Araneae – spiders (40,000 species)
• †Haptopoda – extinct arachnids obviously office of the Tetrapulmonata, the group including spiders and whip scorpions (1 species)
• Opilioacariformes – harvestman-like mites (10 genera)
• Opiliones – phalangids, harvestmen or daddy-long-legs (6,300 species)
• Palpigradi – microwhip scorpions (80 species)
• Parasitiformes – ticks (12,000 species)
• †Phalangiotarbi – extinct arachnids of uncertain affinity (xxx species)
• Pseudoscorpionida – pseudoscorpions (3,000 species)
• Ricinulei – ricinuleids, hooded tickspiders (60 species)
• Schizomida – "divide eye" whip scorpions with divided exoskeletons (220 species)
• Scorpiones – scorpions (2,000 species)
• Solifugae – solpugids, windscorpions, sun spiders or camel spiders (900 species)
• Thelyphonida (likewise called Uropygi) – whip scorpions or vinegaroons, forelegs modified into sensory appendages and a long tail on belly tip (100 species)
• †Trigonotarbida – extinct (late Silurian Early Permian)
• †Uraraneida – extinct spider-similar arachnids, only with a "tail" and no spinnerets (ii species)

It is estimated that 98,000 arachnid species accept been described, and that in that location may be up to 600,000 in total.^[32]

See besides [edit]

• Arachnophobia
• Endangered spiders
• Glossary of spider terms
• Listing of extinct arachnids

References [edit]

1. ^ Cracraft, Joel & Donoghue, Michael, eds. (2004). Assembling the Tree of Life . Oxford University Press. p. 297.
2. ^ "Arachnid". Oxford English Dictionary (2nd ed.). 1989.
3. ^ Brabazon, Anthony (2018). Foraging-Inspired Optimisation Algorithms. Springer International Publishing. p. 237. ISBN9783319591568.
4. ^ Schmidt, Günther (1993). Giftige und gefährliche Spinnentiere [Poisonous and dangerous arachnids] (in German). Westarp Wissenschaften. p. 75. ISBN978-three-89432-405-6.
5. ^ Shultz, Stanley; Shultz, Marguerite (2009). The Tarantula Keeper'south Guide. Hauppauge, New York: Barron'due south. p. 23. ISBN978-0-7641-3885-0.
6. ^ Ruppert, E.; Fox, R. & Barnes, R. (2007). Invertebrate Zoology: A Functional Evolutionary Approach (7th ed.). Thomson Learning. ISBN978-0-03-025982-1.
7. ^ The Colonisation of Country: Origins and Adaptations of Terrestrial Animals
8. ^ Kovoor, J. (1978). "Natural calcification of the prosomatic endosternite in the Phalangiidae (Arachnida:Opiliones)". Calcified Tissue Research. 26 (3): 267–269. doi:10.1007/BF02013269. PMID 750069. S2CID 23119386.
9. ^ ^{a b} Sensenig, Andrew T. & Shultz, Jeffrey Due west. (February fifteen, 2003). "Mechanics of Cuticular Rubberband Energy Storage in Leg Joints Lacking Extensor Muscles in Arachnids". Journal of Experimental Biology. 206 (iv): 771–784. doi:10.1242/jeb.00182. ISSN 1477-9145. PMID 12517993.
10. ^ Shultz, Jeffrey W. (Feb vi, 2005). "Development of locomotion in arachnida: The hydraulic pressure level pump of the giant whipscorpion, Mastigoproctus giganteus (Uropygi)". Journal of Morphology. 210 (i): 13–31. doi:10.1002/jmor.1052100103. ISSN 1097-4687. PMID 29865543. S2CID 46935000.
11. ^ Shultz, Jeffrey West. (Jan ane, 1992). "Muscle Firing Patterns in Two Arachnids Using Different Methods of Propulsive Leg Extension". Journal of Experimental Biological science. 162 (1): 313–329. doi:10.1242/jeb.162.1.313. ISSN 1477-9145. Retrieved 2012-05-19 .
12. ^ Sensenig, Andrew T. & Shultz, Jeffrey W. (2004). "Elastic energy storage in the pedipedal joints of scorpions and sun-spiders (Arachnida, Scorpiones, Solifugae)". Journal of Arachnology. 32 (1): 1–10. doi:10.1636/S02-73. ISSN 0161-8202. S2CID 56461501.
13. ^ Garwood, Russell J. & Edgecombe, Gregory D. (September 2011). "Early Terrestrial Animals, Evolution, and Uncertainty". Evolution: Education and Outreach. 4 (iii): 489–501. doi:ten.1007/s12052-011-0357-y.
14. ^ ^{a b c d e f g} Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 596–604. ISBN978-0-03-056747-half-dozen.
15. ^ ^{a b} Machado, Glauco; Pinto-da-Rocha, Ricardo & Giribet, Gonzalo (2007). Pinto-da-Rocha, Ricardo; Machado, Glauco & Giribet, Gonzalo (eds.). Harvestmen: the Biology of Opiliones. Harvard Academy Press. ISBN978-0-674-02343-7.
16. ^ McLean, Callum J.; Garwood, Russell J.; Brassey, Charlotte A. (2018). "Sexual dimorphism in the Arachnid orders". PeerJ. 6: e5751. doi:10.7717/peerj.5751. ISSN 2167-8359. PMC6225839. PMID 30416880.
17. ^ Meusemann, Karen; Reumont, Björn G. von; Simon, Sabrina; Roeding, Falko; Strauss, Sascha; Kück, Patrick; Ebersberger, Ingo; Walzl, Manfred; Pass, Günther; Breuers, Sebastian; Achter, Viktor; Haeseler, Arndt von; Burmester, Thorsten; Hadrys, Heike; Wägele, J. Wolfgang & Misof, Bernhard (2010). "A Phylogenomic Arroyo to Resolve the Arthropod Tree of Life". Molecular Biological science and Evolution. 27 (11): 2451–2464. doi:10.1093/molbev/msq130. PMID 20534705.
18. ^ ^{a b} Regier, Jerome C.; Shultz, Jeffrey West.; Zwick, Andreas; Hussey, April; Ball, Bernard; Wetzer, Regina; Martin, Joel W. & Cunningham, Clifford Due west. (2010). "Arthropod relationships revealed past phylogenomic analysis of nuclear protein-coding sequences". Nature. 463 (7284): 1079–1083. Bibcode:2010Natur.463.1079R. doi:10.1038/nature08742. PMID 20147900. S2CID 4427443.
19. ^ ^{a b} Rota-Stabelli, Omar; Campbell, Lahcen; Brinkmann, Henner; Edgecombe, Gregory D.; Longhorn, Stuart J.; Peterson, Kevin J.; Pisani, Davide; Philippe, Hervé & Telford, Maximilian J. (2010). "A coinciding solution to arthropod phylogeny: phylogenomics, microRNAs and morphology support monophyletic Mandibulata". Proceedings of the Purple Society of London B: Biological Sciences. 278 (1703): 298–306. doi:10.1098/rspb.2010.0590. PMC3013382. PMID 20702459.
20. ^ Campbell, Lahcen I.; Rota-Stabelli, Omar; Edgecombe, Gregory D.; Marchioro, Trevor; Longhorn, Stuart J.; Telford, Maximilian J.; Philippe, Hervé; Rebecchi, Lorena; Peterson, Kevin J. & Pisani, Davide (2011). "MicroRNAs and phylogenomics resolve the relationships of Tardigrada and advise that velvet worms are the sister group of Arthropoda". Proceedings of the National University of Sciences. 108 (38): 15920–15924. Bibcode:2011PNAS..10815920C. doi:10.1073/pnas.1105499108. PMC3179045. PMID 21896763.
21. ^ ^{a b c d} Sharma, Prashant P.; Kaluziak, Stefan T.; Pérez-Porro, Alicia R.; González, Vanessa Fifty.; Hormiga, Gustavo; Wheeler, Ward C. & Giribet, Gonzalo (2014-01-xi). "Phylogenomic Interrogation of Arachnida Reveals Systemic Conflicts in Phylogenetic Indicate". Molecular Biology and Evolution. 31 (xi): 2963–2984. doi:x.1093/molbev/msu235. PMID 25107551.
22. ^ Legg, David A.; Sutton, Marking D. & Edgecombe, Gregory D. (2013). "Arthropod fossil data increase congruence of morphological and molecular phylogenies". Nature Communications. iv: 2485. Bibcode:2013NatCo...4.2485L. doi:10.1038/ncomms3485. PMID 24077329.
23. ^ Giribet, Gonzalo; Edgecombe, Gregory D. & Wheeler, Ward C. (2001). "Arthropod phylogeny based on eight molecular loci and morphology". Nature. 413 (6852): 157–161. Bibcode:2001Natur.413..157G. doi:10.1038/35093097. PMID 11557979. S2CID 4431635.
24. ^ ^{a b} Ballesteros, J. A.; Sharma, P. P. (2019). "A Critical Appraisal of the Placement of Xiphosura (Chelicerata) with Business relationship of Known Sources of Phylogenetic Error". Systematic Biology. 68 (6): 896–917. doi:ten.1093/sysbio/syz011. PMID 30917194.
25. ^ ^{a b} Wang, B.; Dunlop, J.A.; Selden, P.A.; Garwood, R.J.; Shear, Westward.A.; Müller, P.; Lei, X. (2018). "Cretaceous arachnid Chimerarachne yingi gen. et sp. nov. illuminates spider origins". Nature Ecology & Evolution. 2 (iv): 614–622. doi:10.1038/s41559-017-0449-3. PMID 29403075. S2CID 4239867.
26. ^ Garwood, R.J.; Dunlop, J.A.; Knecht, B.J.; Hegna, T.A. (2017). "The phylogeny of fossil whip spiders". BMC Evolutionary Biological science. 17 (1): 105. doi:10.1186/s12862-017-0931-1. PMC5399839. PMID 28431496.
27. ^ Garwood, R.J.; Dunlop, J.A.; Selden, P.A.; Spencer, A.R.T.; Atwood, R.C.; Vo, N.T.; Drakopoulos, Yard. (2016). "Near a spider: a 305-million-year-old fossil arachnid and spider origins". Proceedings of the Royal Gild B: Biological Sciences. 283 (1827): 20160125. doi:x.1098/rspb.2016.0125. PMC4822468. PMID 27030415.
28. ^ Garwood, R.J.; Dunlop, J. (2014). "Three-dimensional reconstruction and the phylogeny of extinct chelicerate orders". PeerJ. 2: e641. doi:10.7717/peerj.641. PMC4232842. PMID 25405073.
29. ^ Shultz, J.Westward. (2007). "A phylogenetic analysis of the arachnid orders based on morphological characters". Zoological Journal of the Linnean Lodge. 150 (2): 221–265. doi:10.1111/j.1096-3642.2007.00284.x.
30. ^ Selden, P.A.; Shear, W.A. & Sutton, Thou.D. (2008), "Fossil prove for the origin of spider spinnerets, and a proposed arachnid club", Proceedings of the National Academy of Sciences, 105 (52): 20781–20785, Bibcode:2008PNAS..10520781S, doi:10.1073/pnas.0809174106, PMC2634869, PMID 19104044
31. ^ Briggs, Helen (v February 2018). "'Extraordinary' fossil sheds light on origins of spiders". BBC. Retrieved ix June 2018.
32. ^ Chapman, Arthur D. (2005). Numbers of living species in Australia and the world (PDF). Department of the Environment and Heritage. ISBN978-0-642-56850-2.

External links [edit]

Wikimedia Commons has media related to Arachnida.

• Arachnid, Natural History Museum, London

reinerthiscout.blogspot.com

Source: https://en.wikipedia.org/wiki/Arachnid

Share this post