An arthropod is an invertebrate animal having an exoskeleton, a segmented body, paired jointed appendages. Arthropods form the phylum Euarthropoda, which includes insects, arachnids and crustaceans; the term Arthropoda as proposed refers to a proposed grouping of Euarthropods and the phylum Onychophora. Arthropods are characterized by their jointed limbs and cuticle made of chitin mineralised with calcium carbonate; the arthropod body plan consists of each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Arthopods are bilaterally symmetrical and their body possesses an external skeleton; some species have wings. Their versatility has enabled them to become the most species-rich members of all ecological guilds in most environments, they have over a million described species, making up more than 80 per cent of all described living animal species, some of which, unlike most other animals, are successful in dry environments. Arthropods range in size from the microscopic crustacean Stygotantulus up to the Japanese spider crab.
Arthropods' primary internal cavity is a haemocoel, which accommodates their internal organs, through which their haemolymph – analogue of blood – circulates. Like their exteriors, the internal organs of arthropods are built of repeated segments, their nervous system is "ladder-like", with paired ventral nerve cords running through all segments and forming paired ganglia in each segment. Their heads are formed by fusion of varying numbers of segments, their brains are formed by fusion of the ganglia of these segments and encircle the esophagus; the respiratory and excretory systems of arthropods vary, depending as much on their environment as on the subphylum to which they belong. Their vision relies on various combinations of compound eyes and pigment-pit ocelli: in most species the ocelli can only detect the direction from which light is coming, the compound eyes are the main source of information, but the main eyes of spiders are ocelli that can form images and, in a few cases, can swivel to track prey.
Arthropods have a wide range of chemical and mechanical sensors based on modifications of the many setae that project through their cuticles. Arthropods' methods of reproduction and development are diverse; the evolutionary ancestry of arthropods dates back to the Cambrian period. The group is regarded as monophyletic, many analyses support the placement of arthropods with cycloneuralians in a superphylum Ecdysozoa. Overall, the basal relationships of Metazoa are not yet well resolved; the relationships between various arthropod groups are still debated. Aquatic species use either external fertilization. All arthropods lay eggs, but scorpions give birth to live young after the eggs have hatched inside the mother. Arthropod hatchlings vary from miniature adults to grubs and caterpillars that lack jointed limbs and undergo a total metamorphosis to produce the adult form; the level of maternal care for hatchlings varies from nonexistent to the prolonged care provided by scorpions. Arthropods contribute to the human food supply both directly as food, more indirectly as pollinators of crops.
Some species are known to spread severe disease to humans and crops. The word arthropod comes from the Greek ἄρθρον árthron, "joint", πούς pous, i.e. "foot" or "leg", which together mean "jointed leg". Arthropods are invertebrates with jointed limbs; the exoskeleton or cuticles consists of a polymer of glucosamine. The cuticle of many crustaceans, beetle mites, millipedes is biomineralized with calcium carbonate. Calcification of the endosternite, an internal structure used for muscle attachments occur in some opiliones. Estimates of the number of arthropod species vary between 1,170,000 and 5 to 10 million and account for over 80 per cent of all known living animal species; the number of species remains difficult to determine. This is due to the census modeling assumptions projected onto other regions in order to scale up from counts at specific locations applied to the whole world. A study in 1992 estimated that there were 500,000 species of animals and plants in Costa Rica alone, of which 365,000 were arthropods.
They are important members of marine, freshwater and air ecosystems, are one of only two major animal groups that have adapted to life in dry environments. One arthropod sub-group, insects, is the most species-rich member of all ecological guilds in land and freshwater environments; the lightest insects weigh less than 25 micrograms. Some living crustaceans are much larger; the embryos of all arthropods are segmented, built from a series of repeated modules. The last common ancestor of living arthropods consisted of a series of undifferentiated segments, each with a pair of appendages that functioned as limbs. However, all known living and fossil arthropods have grouped segments into tagmata in which segments and their limbs are specialized in various ways; the three-
Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa. Since the cuticle of these animals forms a inelastic exoskeleton, it is shed during growth and a new, larger covering is formed; the remnants of the old, empty exoskeleton are called exuviae. After moulting, an arthropod is described as a callow. Within one or two hours, the cuticle hardens and darkens following a tanning process analogous to the production of leather. During this short phase the animal expands, since growth is otherwise constrained by the rigidity of the exoskeleton. Growth of the limbs and other parts covered by hard exoskeleton is achieved by transfer of body fluids from soft parts before the new skin hardens. A spider with a small abdomen may be undernourished but more has undergone ecdysis; some arthropods large insects with tracheal respiration, expand their new exoskeleton by swallowing or otherwise taking in air. The maturation of the structure and colouration of the new exoskeleton might take days or weeks in a long-lived insect.
Ecdysis allows damaged tissue and missing limbs to be regenerated or re-formed. Complete regeneration may require a series of moults, the stump becoming a little larger with each moult until it is a normal, or near normal, size; the term ecdysis comes from Ancient Greek: ἐκδύω, "to take off, strip off". In preparation for ecdysis, the arthropod becomes inactive for a period of time, undergoing apolysis or separation of the old exoskeleton from the underlying epidermal cells. For most organisms, the resting period is a stage of preparation during which the secretion of fluid from the moulting glands of the epidermal layer and the loosening of the underpart of the cuticle occur. Once the old cuticle has separated from the epidermis, a digesting fluid is secreted into the space between them. However, this fluid remains inactive. By crawling movements, the organism pushes forward in the old integumentary shell, which splits down the back allowing the animal to emerge; this initial crack is caused by a combination of movement and increase in blood pressure within the body, forcing an expansion across its exoskeleton, leading to an eventual crack that allows for certain organisms such as spiders to extricate themselves.
While the old cuticle is being digested, the new layer is secreted. All cuticular structures are shed at ecdysis, including the inner parts of the exoskeleton, which includes terminal linings of the alimentary tract and of the tracheae if they are present; each stage of development between moults for insects in the taxon endopterygota is called an instar, or stadium, each stage between moults of insects in the Exopterygota is called a nymph: there may be up to 15 nymphal stages. Endopterygota tend to have only five instars. Endopterygotes have more alternatives to moulting, such as expansion of the cuticle and collapse of air sacs to allow growth of internal organs; the process of moulting in insects begins with the separation of the cuticle from the underlying epidermal cells and ends with the shedding of the old cuticle. In many species it is initiated by an increase in the hormone ecdysone; this hormone causes: apolysis – the separation of the cuticle from the epidermis secretion of new cuticle materials beneath the old degradation of the old cuticleAfter apolysis the insect is known as a pharate.
Moulting fluid is secreted into the exuvial space between the old cuticle and the epidermis, this contains inactive enzymes which are activated only after the new epicuticle is secreted. This prevents the new procuticle from getting digested; the lower regions of the old cuticle, the endocuticle and mesocuticle, are digested by the enzymes and subsequently absorbed. The exocuticle and epicuticle are hence shed at ecdysis. Spiders change their skin for the first time while still inside the egg sac, the spiderling that emerges broadly resembles the adult; the number of moults varies, both between species and genders, but will be between five times and nine times before the spider reaches maturity. Not since males are smaller than females, the males of many species mature faster and do not undergo ecdysis as many times as the females before maturing. Members of the Mygalomorphae are long-lived, sometimes 20 years or more. Spiders stop feeding at some time before moulting for several days; the physiological processes of releasing the old exoskeleton from the tissues beneath cause various colour changes, such as darkening.
If the old exoskeleton is not too thick it may be possible to see new structures, such as setae, from outside. However, contact between the nerves and the old exoskeleton is maintained until a late stage in the process; the new, teneral exoskeleton has to accommodate a larger frame than the previous instar, while the spider has had to fit into the previous exoskeleton until it has been shed. This means the spider does not fill out the new exoskeleton so it appears somewhat wrinkled. Most species of spiders hang from silk during the entire process, either dangling from a drop line, or fastening their claws into webbed fibres attached to a suitable base; the discarded, dried exoskeleton remains hanging where it was abandoned once the spider has left. To open the old exoskeleton, the spider contracts its abdomen to supply enough fluid to pump into the prosoma with sufficient pressure to crack it open alo
Beetles are a group of insects that form the order Coleoptera, in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, distinguishing them from most other insects; the Coleoptera, with about 400,000 species, is the largest of all orders, constituting 40% of described insects and 25% of all known animal life-forms. The largest of all families, the Curculionidae with some 70,000 member species, belongs to this order. Found in every habitat except the sea and the polar regions, they interact with their ecosystems in several ways: beetles feed on plants and fungi, break down animal and plant debris, eat other invertebrates; some species are serious agricultural pests, such as the Colorado potato beetle, while others such as Coccinellidae eat aphids, scale insects and other plant-sucking insects that damage crops. Beetles have a hard exoskeleton including the elytra, though some such as the rove beetles have short elytra while blister beetles have softer elytra; the general anatomy of a beetle is quite uniform and typical of insects, although there are several examples of novelty, such as adaptations in water beetles which trap air bubbles under the elytra for use while diving.
Beetles are endopterygotes, which means that they undergo complete metamorphosis, with a series of conspicuous and abrupt changes in body structure between hatching and becoming adult after a immobile pupal stage. Some, such as stag beetles, have a marked sexual dimorphism, the males possessing enormously enlarged mandibles which they use to fight other males. Many beetles are aposematic, with bright colours and patterns warning of their toxicity, while others are harmless Batesian mimics of such insects. Many beetles, including those that live in sandy places, have effective camouflage. Beetles are prominent in human culture, from the sacred scarabs of ancient Egypt to beetlewing art and use as pets or fighting insects for entertainment and gambling. Many beetle groups are brightly and attractively coloured making them objects of collection and decorative displays. Over 300 species are used as food as larvae. However, the major impact of beetles on human life is as agricultural and horticultural pests.
Serious pests include the boll weevil of cotton, the Colorado potato beetle, the coconut hispine beetle, the mountain pine beetle. Most beetles, however, do not cause economic damage and many, such as the lady beetles and dung beetles are beneficial by helping to control insect pests; the name of the taxonomic order, comes from the Greek koleopteros, given to the group by Aristotle for their elytra, hardened shield-like forewings, from koleos and pteron, wing. The English name beetle comes from the Old English word bitela, little biter, related to bītan, leading to Middle English betylle. Another Old English name for beetle is ċeafor, used in names such as cockchafer, from the Proto-Germanic *kebrô. Beetles are by far the largest order of insects: the 400,000 species make up about 40% of all insect species so far described, about 25% of all animals. A 2015 study provided four independent estimates of the total number of beetle species, giving a mean estimate of some 1.5 million with a "surprisingly narrow range" spanning all four estimates from a minimum of 0.9 to a maximum of 2.1 million beetle species.
The four estimates made use of host-specificity relationships, ratios with other taxa, plant:beetle ratios, extrapolations based on body size by year of description. Beetles are found in nearly all habitats, including freshwater and coastal habitats, wherever vegetative foliage is found, from trees and their bark to flowers and underground near roots - inside plants in galls, in every plant tissue, including dead or decaying ones; the heaviest beetle, indeed the heaviest insect stage, is the larva of the goliath beetle, Goliathus goliatus, which can attain a mass of at least 115 g and a length of 11.5 cm. Adult male goliath beetles are the heaviest beetle in its adult stage, weighing 70–100 g and measuring up to 11 cm. Adult elephant beetles, Megasoma elephas and Megasoma actaeon reach 50 g and 10 cm; the longest beetle is the Hercules beetle Dynastes hercules, with a maximum overall length of at least 16.7 cm including the long pronotal horn. The smallest recorded beetle and the smallest free-living insect, is the featherwing beetle Scydosella musawasensis which may measure as little as 325 µm in length.
The oldest known fossil insect that unequivocally resembles a Coleopteran is from the Lower Permian Period about 270 million years ago, though these members of the family Tshekardocoleidae have 13-segmented antennae, elytra with more developed venation and more irregular longitudinal ribbing, abdomen and ovipositor extending beyond the apex of the elytra. In the Permian–Triassic extinction event at the end of the Permian, some 30% of all insect species became extinct, so the fossil record of insects only includes beetles from the Lower Triassic 220 mya. Around this time, during the Late Triassic, fungus-feeding species such as Cupedidae appear in the fossil record. In the stages of the Upper Triassic, alga-feeding insects such as Triaplidae and Hydrophilidae begin to appear, alongside predatory water beetles; the first weevils, including the Obrienidae, appear alongside the first rove beetles, which resemb
A blister agent, or vesicant, is a chemical compound that causes severe skin and mucosal pain and irritation. They are named for their ability to cause severe chemical burns, resulting in painful water blisters on the bodies of those affected. Although the term is used in connection with large-scale burns caused by chemical spills or chemical warfare agents, some occurring substances such as cantharidin are blister-producing agents. Furanocoumarin, another occurring substance, causes vesicant-like effects indirectly, for example, by increasing skin photosensitivity greatly. Vesicants have medical uses including wart removal but can be fatal if small amounts are ingested. Most blister agents fall into one of three groups: Sulfur mustards – A family of sulfur-based agents, including mustard gas. Nitrogen mustards – A family of agents similar to the sulfur mustards, but based on nitrogen instead of sulfur. Lewisite – An early blister agent, developed, but not used, during World War I, it was rendered obsolete with the development of British anti-Lewisite in the 1940s.
Phosgene oxime is included among the blister agents, although it is more properly termed a nettle agent. Exposure to a weaponized blister agent can cause a number of life-threatening symptoms, including: Severe skin and mucosal pain and irritation Skin erythema with large fluid blisters that heal and may become infected Tearing, corneal damage Mild respiratory distress to marked airway damageAll blister agents known are denser than air, are absorbed through the eyes and skin. Effects of the two mustard agents are delayed: exposure to vapors becomes evident in 4 to 6 hours, skin exposure in 2 to 48 hours; the effects of Lewisite are immediate. Medterms.com Medical Aspects of Biological and Chemical Warfare, Chapter 7: Vesicants
Binomial nomenclature called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomen, binominal name or a scientific name; the first part of the name – the generic name – identifies the genus to which the species belongs, while the second part – the specific name or specific epithet – identifies the species within the genus. For example, humans belong within this genus to the species Homo sapiens. Tyrannosaurus rex is the most known binomial; the formal introduction of this system of naming species is credited to Carl Linnaeus beginning with his work Species Plantarum in 1753. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus; the application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature for animals and the International Code of Nomenclature for algae and plants.
Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in the terminology they use and in their precise rules. In modern usage, the first letter of the first part of the name, the genus, is always capitalized in writing, while that of the second part is not when derived from a proper noun such as the name of a person or place. Both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a binomial name is given, at least when it is first mentioned, the date of publication may be specified. In zoology "Patella vulgata Linnaeus, 1758"; the name "Linnaeus" tells the reader who it was that first published a description and name for this species of limpet. "Passer domesticus". The original name given by Linnaeus was Fringilla domestica; the ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, although nomenclatorial catalogs include such information.
In botany "Amaranthus retroflexus L." – "L." is the standard abbreviation used in botany for "Linnaeus". "Hyacinthoides italica Rothm. – Linnaeus first named this bluebell species Scilla italica. The name is composed of two word-forming elements: "bi", a Latin prefix for two, "-nomial", relating to a term or terms; the word "binomium" was used in Medieval Latin to mean a two-term expression in mathematics. Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name, from one to several words long. Together they formed a system of polynomial nomenclature; these names had two separate functions. First, to designate or label the species, second, to be a diagnosis or description. In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; such "polynomial names" may sometimes look like binomials, but are different. For example, Gerard's herbal describes various kinds of spiderwort: "The first is called Phalangium ramosum, Branched Spiderwort.
The other... is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia". The Latin phrases are short descriptions, rather than identifying labels; the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné, more known by his Latinized name Carl Linnaeus, it was in his 1753 Species Plantarum that he first began using a one-word "trivial name" together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as specific name; the Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word. Linnaeus's trivial names introduced an important new idea, namely that the function of a name could be to give a species a unique label; this meant. Thus Gerard's Phalangium ephemerum virginianum became Tradescantia virgi
Cantharis is a large genus of soldier beetles in the family Cantharidae with narrow and soft elytra. The poisonous Spanish fly is superficially similar and is associated with the scientific name Cantharis vesicatoria, it is sometimes called "cantharis" in the vernacular, but it is unrelated to Cantharis and is not a member of the Cantharidae at all. It was classified there erroneously until Johan Christian Fabricius corrected its name in his Systema entomologiae in 1775, he reclassified the Spanish fly in the new genus Lytta as Lytta vesicatoria. It belongs to the family Meloidae. Cantharis gemina Dahlgren, 1974 Cantharis lateralis Linnaeus, 1758 Cantharis pagana Rosenhauer, 1847 List of Cantharis species Wittmer W. Kasantsev S. On the classification of the genus Cantharis Linné. Entomologica Basiliensia 20: 367-372. Biolib Fauna europaea
Ligustrum obtusifolium is a species of privet, native to Japan and northeastern China. The species is considered invasive in parts of the United States, it has become common in southern New England, the mid-Atlantic States, the Great Lakes regions, with scattered occurrences in the South, the Great Plains, Washington State. Ligustrum obtusifoliumis a deciduous shrub growing to 3 metres tall; the leaves are 4 to 25 millimetres broad. There are three subspecies: Ligustrum obtusifolium subsp. Obtusifolium. Japan. Ligustrum obtusifolium subsp. Microphyllum P. S. Green. Eastern China, Japan. Ligustrum obtusifolium subsp. Suave Kitagawa. Northeastern China. Ligustrum means ‘binder’, it was named by Pliny and Virgil