Arachnida is a class of joint-legged invertebrate animals, in the subphylum Chelicerata. Spiders are the largest order in the class, which includes scorpions, mites and solifuges. In 2019, a molecular phylogenetic study placed horseshoe crabs in Arachnida. All adult arachnids have eight legs, although the front pair of legs in some species has converted to a sensory function, while in other species, different appendages can grow large enough to take on the appearance of extra pairs of legs; the term is derived from the Greek word ἀράχνη, from the myth of the hubristic human weaver Arachne, turned into a spider. All extant arachnids are terrestrial, living on land. However, some inhabit freshwater environments and, with the exception of the pelagic zone, marine environments as well, they comprise over 100,000 named species. All adult arachnids have eight legs, unlike adult insects which all have six legs. However, arachnids have two further pairs of appendages that have become adapted for feeding and sensory perception.
The first pair, the chelicerae, serve in defense. The next pair of appendages, the pedipalps, have been adapted for feeding, and/or reproductive functions. In Solifugae, the palps are quite leg-like; the larvae of mites and Ricinulei have only six legs. However, mites are variable: as well as eight, there are adult mites with six or four legs. Arachnids are further distinguished from insects by the fact, their body is organized into two tagmata, called the prosoma, or cephalothorax, the opisthosoma, or abdomen. The cephalothorax is derived from the fusion of the cephalon and the thorax, is covered by 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 divided into a preabdomen and postabdomen, although this is only visible in scorpions, in some orders, such as the Acari, the abdominal sections are fused. A telson is present in scorpions, where it has been modified to a stinger, in the Schizomida, whip scorpions and Palpigradi.
Like all arthropods, arachnids have an exoskeleton, they have an internal structure of cartilage-like tissue, called the endosternite, to which certain muscle groups are attached. The endosternite is calcified in some Opiliones. 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. Solifuges and some harvestmen extend their knees by the use of elastic thickenings in the joint cuticle. Scorpions and some harvestmen have evolved muscles that extend two leg joints at once; the equivalent joints of the pedipalps of scorpions though, are extended by elastic recoil. There are characteristics that are 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. While the tracheae are individual systems of tubes, similar to those in insects, ricinuleids 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 system has certainly evolved from the book lungs, indicates that the tracheae of arachnids are not homologous with those of insects. Further adaptations to terrestrial life are appendages modified for more efficient locomotion on land, internal fertilisation, special sensory organs, 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, one or two pairs of Malpighian tubules, emptying into the gut. Many arachnids have the other type of excretory gland, although several do have both; the primary nitrogenous waste product in arachnids is guanine. Arachnid blood is variable in composition, depending on the mode of respiration. Arachnids with an efficient tracheal system do not need to transport oxygen in the blood, may have a reduced circulatory system. In scorpions and some spiders, 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, may or may not be segmented. Some mites have no heart at all. Arachnids are carnivorous, feeding on the pre-digested bodies of insects and other small animals. Only in the harvestmen and among mites, such as the house dust mite, is there ingestion of solid food particles, thus exposure to internal parasites, although it is not unusual for spiders to eat their own silk. Several groups secrete venom from specialized glands to kill prey or enemies. Several mites and ticks are parasites. Arachnids produce digestive juices in their stomachs, use their pedipalps and chelicerae to pour them over their dead prey; the digestive juices turn the prey into a broth of nutrients, which the arachnid sucks into a pre-buccal cavity located in front of the mouth. Behind the mouth is a muscular, sclerotised pharynx, which acts as a pump, sucking the food through the mouth and on into the oesophagus and stomach. In some arachnids, the oesophagus acts as an additional pump.
The stomach is tubular in shape
The grammar of the Otomi language displays a mixture of elements of synthetic and analytic structures. The phrase-level morphology is synthetic, whereas the sentence-level is analytic; the language is head-marking in terms of its verbal morphology, but not in its nominal morphology, more analytic. Otomi recognizes three large open word classes of nouns and particles. There is a small closed class of property words, variously analyzed as adjectives or stative verbs. According to the most-common analysis, the Otomi language has two kinds of bound morphemes and affixes. Proclitics differ from affixes in their phonological characteristics – they are marked for tone and block nasal harmony; some authors consider proclitics to be better analyzed as prefixes. Orthographically, the standard orthography writes proclitics as separate words, whereas affixes are written joined to their host root. Most affixes are suffixes and with few exceptions occur only on verbs, whereas the proclitics occur both in nominal and verbal paradigms.
Proclitics mark the categories of definiteness and number, negation and aspect – fused in a single proclitic. Suffixes mark direct and indirect objects, as well as clusivity, number and affective emphasis; as in other Oto-Manguean languages, the basic word order is verb–subject–object, but some dialects tend towards subject–verb–object word order under influence from Spanish. Possessive constructions use the order possessed-possessor but modificational constructions use modifier-head order; the phonemic orthography employed for writing Otomi in this article is the one used by Lastra. It includes tones in order to be maximally informative, but many practical orthographies used by Otomi speakers do not include information about tone; the symbols used to write the tones in the examples are acute accent /´/ for high tone, circumflex accent /^/ for ascending tone. The symbols used for the four nasal vowels are /į, ę, ą, ų/; the consonant symbols: /c/ denotes IPA, /y/ denotes IPA. The remaining symbols are from the IPA with their original values.
The pronominal system of most Otomi varieties distinguish four persons: first inclusive and exclusive and third, three numbers singular and plural. The system below is from the Toluca dialect. Otomi nouns are inflected for possession, for diminutive; the particular pattern of possessive inflection is widespread throughout the Mesoamerican Linguistic Area. A possessed noun is prefixed with a morpheme agreeing in person with the possessor. If the possessor is plural or dual, the noun is marked with a suffix agreeing with the possessor's number. Below is given the inflectional paradigm for the word /ngų´/ "house" in the dialect of Toluca. To express plurality of a possessed noun, a periphrastic construction is used. Kʔɨ mą-ngų´ "my houses" those I-housePossession can be emphatic, in which case it adds an emphatic suffix -gó -gé or -gégé and adds as a prefix the word mɛhti "possession". Ni rʌ ʔbɛ^cʔé mą-mɛ´hti-gó-ní "that basket is mine" that the basket I-possession-me-thatni rʌ ʔbɛ^cʔé rʌ-mɛ´hti-gégé-ní "that basket is his/hers" that the basket He/she-possession-her/him-thatThe diminutive is inflected by a prefix ci- ci-nú "little house" diminutive-house Plurality of nouns is expressed with articles preceding the noun, rʌ "the" or yʌ "the": In addition to the simple plural/singular articles, the Classical Otomi language as described by Cárceres distinguished honorific and pejorative articles.
In classical Otomi, the articles were ąn "neutral singular", e, nø^ yo and o. ąn ngų´ "the house"nø^ ngų´ "the damn house"o ngų´ "the honored house" On verbs, all of the categories of person of subject, tense and mood are marked by the means of a single prefix on each verb. In Otomi of Toluca and of Ixtenco, the categories distinguished are present, perfect, future, two different subjunctives and past continuative and imperative. Mezquital Otomi has additional moods. On transitive verbs, person of the object is inflected by a suffix. If either subject or object is dual or plural, it is shown with a plural suffix following the object suffix; the structure of the Otomi verb is as follows: The present tense prefixes are di-, gi-, i-. The preterit uses the prefixes do-, go- and bi-, perfect uses to-, ko-, ʃi-, imperfect uses dimá, gimá, mi, future uses go-, gi- and da- and pluperfect tamą-, kimą-, kamą-. All tenses use clusivity as the present tense; the difference between preterit and imperfect is similar to the distinction between the preterit in Spanish habló "he spoke" and the imperfect hablaba "he spoke/He used to speak/he was speaking".
In Toluca Otomi, the semantic differences between the two subjunctive forms are not defined. Both have the meaning of something counterfactual. However, in other Otomi varieties, e.g. Otomi of Ixtenco Tlaxcala, the distinction between the two forms is one of subjunctive vs. irrealis. The past and present progressive are similar in meaning to English is X-ing respectively; the imperative is for issuing direct orders. Verbs expressing movement towards the speaker such as ʔįhį "come" use a different set of prefixes for marking person/
SOLVE is an environmental non-profit organization working throughout the U. S. state of Oregon. The group is based in Portland SOLVE was founded in 1969 by Oregon Governor Tom McCall with the goal of reducing and cleaning up litter and vandalism throughout Oregon. In 1976, SOLVE hired Blanche Schroeder, Portland Chamber of Commerce lobbyist, to act as Executive Director of SOLVE on a part-time basis; the first statewide citizen volunteer Beach Cleanup in the nation was organized by SOLVE in 1984. Since annual beach cleanups have spread to every state in the U. S. all U. S. territories, more than 100 countries around the world. Jack McGowan became the director of the group in 1990, continued as its leader until 2008. Over time, SOLVE has expanded its work to include education efforts, removal of invasive species, planting of native species. In April 2008, Dianna Smiley took over as director after McGowan retired, she was replaced in January 2010 by Melisa McDonald; the current Executive Director is Maureen Fisher.