Arachnida (/ əˈræknɪdə /) is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes orders containing spiders (the largest order), scorpions, ticks, mites, harvestmen, and solifuges. In 2019, a molecular phylogenetic study also placed horseshoe crabs in Arachnida.
- Morphology
Almost all adult arachnids have eight legs, unlike adult...
- Physiology
There are characteristics that are particularly important...
- Diet and digestive system
Arachnids are mostly carnivorous, feeding on the...
- Senses
Arachnids have two kinds of eyes: the lateral and median...
- Reproduction
Arachnids may have one or two gonads, which are located in...
- Solifugae
Solifugae is an order of animals in the class Arachnida...
- Opiliones Harvestmen
The Opiliones are known for having exceptionally long legs...
- Chelicerata
The subphylum Chelicerata (New Latin, from French chélicère,...
- Morphology
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- Definition
- Anatomy
- Physiology
- Diet and Digestive System
- Myth
- Orders
- Images
Arachnids are defined as coming from the class of Arachnida. The requirements for this class is to have two body regions; a cephalothorax and an abdomen; 4 pairs of legs; and 2 pairs of mouthpart appendages, the chelicerae and the pedipalps.
All adult arachnids have four pairs of legs, and arachnids may be easily distinguished from insects by this fact, since insects have three pairs of legs. However, arachnids also have two further pairs of appendages that have become adapted for feeding, defense, and sensory perception. The first pair, the chelicerae, serve in feeding and defense. The next pair of appendages, the pedipalps have been adapted for feeding, locomotion, and/or reproductivefunctions. Like all arthropods, arachnids have an exoskeleton. They also have an internal structure of cartilage-like tissue, to which certain muscle groups are attached. Arachnids have no antennae or wings. Their body is organized into two parts: the cephalothorax, and the abdomen.
There are some adaptations for life on land. They have internal respiratory surfaces. These may be trachea (tubes), or a modification of gills into a 'book lung'. This is an internal series of lamellaeused for gas exchange with the air.
Arachnids are mostly carnivorous, feeding on the pre-digested bodies of insects and other small animals. Only the harvestmen and some mites eat solid food particles. Predigestion avoids exposure to internal parasites. Several groups secrete venom from specialized glands to kill prey or enemies. Several mites are external parasites, and some of them are carriers of disease (vectors). Arachnids pour digestive juices produced in their stomachs over their prey after killing it with their pedipalps and chelicerae. 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, pharynx, which acts as a pump, sucking the food through the mouth and on into the oesophagus and stomach. In some arachnids, the oesophagus also acts as an additional pump.
The word Arachnida comes from the Greek for 'spider'. In legend, a girl called Arachne was turned into a spider by the goddess Athena. Arachne said she'd win a weaving contestagainst the goddess. Athena won, but Arachne became angry, and started to weave an insult to the gods. Then Athena turned her into a spider for her disrespect.
The subdivisions of the arachnids are usually treated as orders. Historically, mites and tickswere treated as a single order, Acari. However, molecular phylogenetic studies suggest that the two groups do not form a single clade; morphological similarities are probably due to convergence. They are now usually treated as two separate 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. 1. Acariformes– mites (32,000 species) 2. 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) 3. Araneae– spiders (40,000 species) 4. †Haptopoda – extinct arachnids apparently part of the Tetrapulmonata, the group including spiders and whip scorpions (1 species) 5. Opilioacariformes– harvestman-like mites (10 genera) 6. Opiliones– phalangids, harvestmen or daddy-long-l...
A scorpion (Sc. Maurus Palmatus)Galeodes, a camel spiderA whip scorpionA Pseudoscorpion, on a printed page- Arachnida
- Arthropoda
Arachnid is a 2001 American horror film directed by Jack Sholder. The film centers on a group of plane crash survivors who are stalked and killed by giant alien spiders. The film stars Alex Reid, Chris Potter, Rocqueford Allen, Robert Vicencio and José Sancho.
- Francesc Gener
- Brian Yuzna
- June 29, 2001
- Alex Reid, Chris Potter, Rocqueford Allen, Robert Vicencio, José Sancho
Look up arachnid in Wiktionary, the free dictionary. An arachnid is a member of a class of joint-legged invertebrate animals. Arachnid may also refer to: Arachnid Solitaire or Spider, a solitaire card game
- Overview
- Spiders
- Scorpions
- Mites
- Processing
Some arachnids may be used for human consumption, either whole or as an ingredient in processed food products such as cheese. Arachnids include spiders, scorpions, and mites.
About 15 species of spiders are scientifically described as being edible, with a history of human consumption. These edible spiders include: 1. Thailand zebra leg tarantula which is sold fried as traditional snack in Cambodia and Thailand; 2. Thailand Black; 3. Goliath birdeater; 4. several other species of tarantula; 5. the golden orb-weaving spider that is eaten in New Caledonia and is said to taste like pâté.
Fried scorpion is traditionally eaten in Shandong, China.
Milbenkäse is a German speciality cheese. Mimolette is a mite cheese traditionally produced around the city of Lille, France. Cheese mites could cause an allergic reaction if consumed in large quantities.
Typical processing of arachnids as food includes heating, defanging and, in certain cases, drying and grinding.
Arachnid Frae Wikipedia, the free beuk o knawledge Arachnids are a cless (Arachnida) o jynt-legged invertebrate animals in the subphylum Chelicerata.
- Arachnida, Lamarck, 1801
- Arthropoda
- Overview
- Hydraulics
- Elastics
- Influence on biomimetic design
- Fluid secretion
- Challenges in modelling
Arachnid locomotion is the various means by which arachnids walk, run, or jump; they make use of more than muscle contraction, employing additional methods like hydraulic compression. Another adaptation seen especially in larger arachnid variants is inclusion of elastic connective tissues.
In most arachnids, hydraulic compression acts as the primary means of extension in several of their hinged leg joints, namely the femur–patella joint and tibia–metatarsus joints or second and third leg joints respectively. Instead of blood, hemolymph is used to move nutrients around inside of the arachnid, and has the secondary function of acting as a hydraulic fluid. When compressed by the body of the arachnid, the hemolymph applies compressive force through channels in the limbs that ...
In larger variants of arachnids, such as the tarantulas and hairy desert spiders, another mechanism used for locomotion is an elastic sclerite. These sclerites are semi-rigid connectors between leg segments that allow storage and expending of potential energy. This is used as a supplement or in conjunction with the hydraulics normally employed in those joints, allowing for greater weights to be carried, more rapid and sudden movement when combined with the already pronounced flexor muscle acting
Hydraulic locomotion in arachnids has acted as an inspiration for many modern biomimetic concepts in robotics intended for use by or with people, especially in the field of soft robotics. The use of hydraulics in robotic joints is aimed at replacing the more control heavy nature of modern robotics with a more passive system developed in soft actuation. Various forms of actuation and force transmission can be achieved through these inspired designs, including rotation, lifting, and even damping e
An additional method used by some arachnids to improve locomotion is to secrete fluids, characterized by a hydrophobic effect, through the pads on the ends of their legs that are in contact with the walking surface. It has been shown that the arachnid is capable of using the adhesive fluid selectively, meaning it can choose to not secrete the fluid in certain circumstances where it would be unwarranted such as in moist conditions. The use of fluids allow the arachnid better traction through impr
Modelling the hydraulic system used by arachnids has been a challenge in the past due to scale and complexity. Simplified models focusing on individual joints and flow channels using modern imaging such as Micro-CT has allowed for mathematical expressions of pressure and flow acting on the joints. Visualizing the flow of hemolymph in small bodies directly has been difficult due to resolution constraints and lack of contrast causing fluid and soft tissue being indistinguishable, but techniques ha
Deng arachnids, Arachnida, metung lang uri da reng animal a en:invertebrate king subphylum a Chelicerata. Pekilagyu do reng arachnid king tauan king mitolohiya ning Grecia a maki lagyung Arachne. Keraklan kareti, arthropod a king gabun manuknangan.
Arachnophobia may be an exaggerated form of an instinctive response that helped early humans to survive or a cultural phenomenon that is most common in predominantly European societies.
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Arachnid
Class of arthropods
Arachnida is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes orders containing spiders (the largest order), scorpions, ticks, mites, harvestmen, and solifuges. In 2019, a molecular phylogenetic study also placed horseshoe crabs in Arachnida. en.wikipedia.org
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