snake eel: The spotted snake eel (Ophichthus ophis) of the southern Atlantic and Caribbean attains a length of 120 centimetres (4 feet).

ophicleide, brass wind musical instrument with a cup-shaped mouthpiece and padded keys, the bass version of the old keyed bugle. The name (from Greek ophis and kleid, “serpent” and “key”) alludes to its improvement on the military band “upright serpents” (now-obsolete S-shaped bass instruments

cusk eel, any of about 30 species of slim, eel-like marine fishes of the family Ophidiidae, found worldwide in warm and temperate waters. Cusk eels are characterized by the union of their dorsal, anal, and tail fins into a single long fin, and by the position of their feeler-like pelvic fins, which

paracanthopterygian: General features: …and about 385 species of ophidiiforms (that is, the pearlfishes and cusk-eels).

paracanthopterygian: General features: …and about 385 species of ophidiiforms (that is, the pearlfishes and cusk-eels).

avoidance behaviour: Specific stimuli: …disturbed by the sight of snakes—the notion of a legless object perhaps being a key stimulus. Human responses to spiders and centipedes with conspicuous legs also may be intense. In the reaction to snakes at least, notwithstanding Freudian explanations that they symbolize male sex organs, the behaviour of people may…

Sabiaceae: …and is known as the snake nut. Meliosma, with about 80 species, has two anthers that open explosively after being held under tension by two or three complex staminodes (sterile stamens). Sabia, with some 30 species, and the small genus Kingsboroghia are the other two genera of the family.

echinoderm: Annotated classification: †Class Ophiocistioidea Lower Ordovician to Upper Silurian about 395,000,000–500,000,000 years ago; dome-shaped body partly or completely covered by well-developed test; 5 ambulacral tracts carry plated tube feet relatively enormous in size. Class Holothuroidea (sea cucumbers) Fossil and living forms (Ordovician about 460,000,000

Zombie-ant fungusA deceased carpenter ant (Camponotus species) infected with zombie-ant fungus (Ophiocordyceps unilateralis). Having acted under the influence of the fungus, the ant is attached to the midrib of a leaf in the characteristic “death grip,” which allows the fungal spores to be

brittle star: …best-known littoral species are the green brittle star (Ophioderma brevispina), found from Massachusetts to Brazil, and the common European brittle star (Ophiothrix fragilis). Brittle stars typically hide under rocks or in crevices during the day and emerge at night to feed.

lingcod, (Ophiodon elongatus), commercially popular species of fish in the family Hexagrammidae (order Scorpaeniformes). A voracious predator, the lingcod has a large mouth and canine-like teeth for eating fishes and other aquatic prey, including squid. The species is strictly marine, occurring

Ophioglossaceae, family of four or five genera and about 100 species of primitive ferns (order Ophioglossales). The plants are largely terrestrial with a few epiphytic species and are found throughout tropical and temperate regions. The taxonomy of the group is contentious. Its members are

plant: Annotated classification: Class Psilotopsida (whisk ferns) Vascular plants; sporophyte lacking roots and often leaves; stems with small enations, dichotomously branched; vascular tissue forming a central core in stem (protostelic); sporangia fused into synangiate structure, apparently terminal on short stem; homosporous; gametophytes subterranean, with motile sperm; representative genus, Psilotum

Ophioglossaceae: The genus Ophioglossum (adder’s-tongue ferns), with 46 tropical and temperate species, has sporangia in two rows near the tip of a usually unbranched narrow fertile spike. The group is of interest because its members have the highest number of chromosomes of any organisms known to science; O. reticulatum…

Ophioglossaceae: … is an Indian species (O. malviae), reaching an average size of only 1–1.2 cm (0.39–0.47 inch).

fern: Chromosome numbers and polyploidy: Ophioglossum reticulatum has 1,440 chromosomes, the highest number of any organism known to science. Among homosporous ferns, exceptions to the rule of high chromosome numbers are rare; in one species of filmy fern (Hymenophyllum peltatum), x = 11, the lowest number reported. Among heterosporous ferns,…

igneous rock: Divergent plate boundaries: …ultramafic rocks are known as ophiolites. Many geologists believe that ophiolites formed at oceanic ridges were emplaced by tectonic forces at convergent plate boundaries and then became exposed in highly deformed orogenic (mountain) belts. In fact, the same sequences of rocks were first reported in the Alps and were considered…

king cobra, (genus Ophiophagus), reptile genus containing the world’s largest venomous snakes. King cobras are found predominantly in forests from India through Southeast Asia to the Philippines and Indonesia. The snake’s maximum confirmed length is 5.6 metres (18 feet), but most do not exceed 3.6

king cobra: …Ghats of southwestern India; the Sunda king cobra (O. bungarus), which can be found from the Malay Peninsula to the Greater Sunda Islands and the southern Philippines; and the Luzon king cobra (O. salvatana), which occurs only on the island of Luzon.

king cobra: …divided into four species: the northern king cobra (O. hannah), whose geographic range spans eastern Pakistan and northern and eastern India; the Western Ghats king cobra (O. kaalinga), which inhabits upland habitats in the Western Ghats of southwestern India; the Sunda king cobra (O. bungarus), which can be found from…

king cobra: …northern and eastern India; the Western Ghats king cobra (O. kaalinga), which inhabits upland habitats in the Western Ghats of southwestern India; the Sunda king cobra (O. bungarus), which can be found from the Malay Peninsula to the Greater Sunda Islands and the southern Philippines; and the Luzon king cobra…

king cobra: …the southern Philippines; and the Luzon king cobra (O. salvatana), which occurs only on the island of Luzon.

Dutch elm disease: …ascomycete fungi in the genus Ophiostoma. One of these, O. ulmi (also known as Ceratocystis ulmi), was probably introduced into Europe from Asia during World War I. The disease was first identified in the United States in 1930. A federal eradication campaign in the late 1930s and early ’40s sharply…

Dutch elm disease: The third species, O. himal-ulmi, was discovered in 1993 and is endemic to the Himalayas.

Dutch elm disease: …late 1940s, another virulent species, O. novo-ulmi, was described in Europe and the United States, and heavy elm losses continued. This species was introduced to Auckland, New Zealand, in 1989, where it was nearly eradicated with aggressive control measures; the country suffered a major outbreak in 2013 due to a…

Ascomycota: necator), Dutch elm disease (Ophiostoma ulmi), chestnut blight (Cryphonectria parasitica), and apple scab (Venturia inequalis).

fungus: Annotated classification: Order Ophiostomatales Pathogenic on plants, causing diseases such as Dutch elm disease and oak wilt; long, tubular ascomata with ostiole at the tip, through which spores are released; included in subclass Sordariomycetidae; examples of genera include Ophiostoma and Fragosphaeria. Order Sordariales Mainly

brittle star: …Massachusetts to Brazil, and the common European brittle star (Ophiothrix fragilis). Brittle stars typically hide under rocks or in crevices during the day and emerge at night to feed.

Tínos, island in the Cyclades (Modern Greek: Kykládes) group of Greek Aegean islands; in antiquity it was known as the “island of the winds,” the modern name being derived from the Phoenician tenok, meaning “snake”; in ancient times it was also called Ophiousa. It constitutes a dímos (municipality)

Ophir, unidentified region famous in Old Testament times for its fine gold. The geographic list of Genesis 10 apparently places it in Arabia, but in the time of Solomon (c. 920 bc), Ophir was thought of as being overseas. Gold, almug (or algum) wood (i.e., sandalwood), ivory, monkeys, and peacocks

glass lizard, any lizard of the genus Ophisaurus in the family Anguidae, so named because the tail is easily broken off. The Eastern glass lizard, Ophisaurus ventralis, occurs in southeastern North America and grows to about 105 cm (41 inches). Together, the lizard’s head and body account for only

glass lizard: It closely resembles the slender glass lizard, O. attenuatus, which has a broader distribution in southeastern North America northwestward into the upper Mississippi River valley. Unlike O. ventralis, which has a broad band along each lower side, O. attenuatus has narrow dark lines.

glass lizard: The Eastern glass lizard, Ophisaurus ventralis, occurs in southeastern North America and grows to about 105 cm (41 inches). Together, the lizard’s head and body account for only 30 to 35 percent of its total length. It has no legs but is easily distinguished from a…

Ophite, (from Greek ophis, “serpent”), member of any of several Gnostic sects that flourished in the Roman Empire during the 2nd century ad and for several centuries thereafter. A variety of Gnostic sects, such as the Naassenes and Cainites, are included under the designation Ophites. These sects’

diabase: …the characteristic texture known as diabasic or ophitic. The larger pyroxene grains may completely enclose plagioclase; but as the quantity of the latter increases, pyroxene appears more interstitial.

science fiction: Alternative societies: John Varley’s The Ophiuchi Hotline (1977) is an archive of methods to shatter old human verities: characters die and are reborn as clones, change sex with ease and alacrity, make backup tapes of their personalities, and undergo drastic acts of surgery—all in a space-dwelling society that accepts…

Ophiuchus, constellation at about 17 hours right ascension and on the celestial equator in declination. Its brightest star is Rasalhague (from the Arabic for “the head of the serpent collector”), with a magnitude of 2.1. This constellation contains Barnard’s Star, the second nearest star to Earth

brittle star, any of the 2,100 living species of marine invertebrates constituting the subclass Ophiuroidea (phylum Echinodermata). Their long, thin arms—usually five and often forked and spiny—are distinctly set off from the small disk-shaped body. The arms readily break off but soon regrow—i.e.,

Ophrys, genus of about 30 species of orchids (family Orchidaceae) native to Eurasia and North Africa. All have metallic-coloured hairy flowers that resemble the females of various insect species and use sexual deception as a means of pollination. The fly orchid (Ophrys insectifera) and the bee

Ophrys: …orchid (Ophrys insectifera) and the bee orchid (O. apifera) are common European species. Some species of Ophrys are known as spider orchids because their flower lips resemble the bodies of spiders.

Ophrys: The fly orchid (Ophrys insectifera) and the bee orchid (O. apifera) are common European species. Some species of Ophrys are known as spider orchids because their flower lips resemble the bodies of spiders.

lying: Defining lying: The mirror orchid (Ophrys speculum) produces blossoms that mimic the form and scent of the female of a species of wasp. This induces male wasps of the species to engage in pseudo-copulations with the blossoms and thereby transport pollen from flower to flower. If it is legitimate to…

human nervous system: Ophthalmic nerve: The ophthalmic nerve passes through the wall of the cavernous sinus and enters the orbit via the superior orbital fissure. Branches in the orbit are (1) the lacrimal nerve, serving the lacrimal gland, part of the upper eyelid, and the conjunctiva, (2) the…

ophthalmology, medical specialty dealing with the diagnosis and treatment of diseases and disorders of the eye. The first ophthalmologists were oculists. These paramedical specialists practiced on an itinerant basis during the Middle Ages. Georg Bartisch, a German physician who wrote on eye

Hermann von Helmholtz: Early life: …were the ophthalmoscope and the ophthalmometer (or keratometer), both made in 1851. (English mathematician and inventor Charles Babbage developed an instrument in 1847 that closely resembled the ophthalmoscope.) While doing work on the eye, and incidentally showing that it was a rather imperfect piece of workmanship not at all consonant…

ophthalmoplegia, paralysis of the extraocular muscles that control the movements of the eye. Ophthalmoplegia usually involves the third (oculomotor), fourth (trochlear), or sixth (abducens) cranial nerves. Double vision is the characteristic symptom in all three cases. In oculomotor paralysis the

ophthalmoscope, instrument for inspecting the interior of the eye. The ophthalmoscope generally is considered to have been invented in 1851 by the German physiologist Hermann von Helmholtz, though it is sometimes credited to English mathematician and inventor Charles Babbage, who in 1847 developed

Max Ophüls was a German motion-picture director whose mastery of fluid camera movement gave his films a characteristic lyrical flow. He was one of the first truly international directors, sensitive to national differences and to the human qualities common to all his characters. Ophüls was an actor,

opioid: Classification: … is sometimes used interchangeably with opiate; the latter, however, refers more narrowly to natural opioids—namely codeine, heroin, morphine, and opium. Opioids and opiates are classified as narcotics, which are any drugs

Ops: … on December 19 and the Opiconsiva on August 25) illustrate her affinities with the Saturnalia (December 17) and the Consualia (of Consus; December 15).

Helena Modjeska was a Polish-American actress whose repertory included 260 Shakespearean and contemporary roles, some in both Polish and English. The daughter of a musician, she married an actor, Gustav Modrzejewski, and they joined a company of strolling players. In 1868 she married Count Bozenta

Amelia Opie was a British novelist and poet whose best work, Father and Daughter (1801), influenced the development of the 19th-century popular novel. Opie was the daughter of a physician. She had no formal schooling but moved in intellectual circles that included William Godwin, Mary

Eugene Lindsay Opie was an American pathologist who conducted important research on the causes, transmission, and diagnosis of tuberculosis and on immunization against the disease. Opie received his M.D. from Johns Hopkins University in 1897, after which he took a position in the pathology

John Opie was an English portrait and historical painter popular in England during the late 18th century. Opie received art instruction from John Wolcot (“Peter Pindar”) in Truro from about 1775 and in 1781 was successfully launched in London as the “Cornish wonder,” a self-taught genius. Opie

commesso: …successor, Ferdinando I, founded the Workshop for Hard Stone (Opificio delle Pietre Dure) as a permanent commesso workshop. The first group of artists employed there perfected the art of making commesso pictures in highly illusionistic perspective. The Workshop was primarily engaged throughout the 17th century in manufacturing decorations for the…

Ernst Öpik was an Estonian astronomer who was best known for his studies of meteors and meteorites and whose life work was devoted to understanding the structure and evolution of the cosmos. In 1916 Öpik received his degree in astronomy from Moscow University. In 1919 he joined the staff of the

Ernst Öpik was an Estonian astronomer who was best known for his studies of meteors and meteorites and whose life work was devoted to understanding the structure and evolution of the cosmos. In 1916 Öpik received his degree in astronomy from Moscow University. In 1919 he joined the staff of the

Santalales: Families: Opiliaceae is a tropical woody family of 12 genera and about 35 species. Its leaves are usually two-ranked (distichous), and they barely show any venation on the blades. Many have small bumps caused by the presence of crystal bodies or cystoliths. Their flowers are small,…

arachnid: Annotated classification: Superorder Opilioacariformes or order Opilioacarida found in North America and parts of the Mediterranean region, all of 1 family. Body of 12 segments, divided into hairy anterior portion with 2 or 3 pairs of eyes.

arachnid: Annotated classification: Superorder Opilioacariformes or order Opilioacarida found in North America and parts of the Mediterranean region, all of 1 family. Body of 12 segments, divided into hairy anterior portion with 2 or 3 pairs of eyes.

daddy longlegs, (order Opiliones), any of more than 6,000 species of arachnids (class Arachnida) that are known for their extremely long and thin legs and for their compact bodies. Daddy longlegs are closely related to scorpions (order Scorpiones) but, because of their appearance, are often

law of war: Law by custom: …and in the belief (called opinio juris: “opinion of the law”) that that practice is in conformity with international law. Much of this customary international law has found its way into the various conventions described above. Therefore, it may properly be argued that, although a particular state is not a…

belief, a mental attitude of acceptance or assent toward a proposition without the full intellectual knowledge required to guarantee its truth. Believing is either an intellectual judgment or, as the 18th-century Scottish Skeptic David Hume maintained, a special sort of feeling with overtones that

China: Unification: …and other advisers—collectively known as opinion officials—whose function was to provide separate channels of information and to check up on the administrative branches.

opinion poll, a method for collecting information about the views or beliefs of a given group. Information from an opinion poll can shed light on and potentially allow inferences to be drawn about certain attributes of a larger population. Opinion polls typically involve a sample of respondents,

public opinion: Opinion research: Opinion research developed from market research. Early market researchers picked small samples of the population and used them to obtain information on such questions as how many people read a given magazine or listen to the radio and what the public likes and dislikes in regard to various consumer…

public opinion, an aggregate of the individual views, attitudes, and beliefs about a particular topic, expressed by a significant proportion of a community. Some scholars treat the aggregate as a synthesis of the views of all or a certain segment of society; others regard it as a collection of many

Roxane Gay: Hunger, Not That Bad, and other works: In 2023 Gay published Opinions: A Decade of Arguments, Criticisms, and Minding Other People’s Business, a collection of some of her most renowned essays and opinion pieces.

opioid, class of drugs derived from substances that occur naturally in the opium poppy (Papaver somniferum) and that are widely used for pain relief and sedation. Opioid drugs include prescription pain relievers, such as fentanyl, oxycodone, and hydrocodone, and illegal substances, such as heroin

analgesic: Opioid analgesics: The term opioid has been adopted as a general classification of all those agents that share chemical structures, sites, and mechanisms of action with the endogenous opioid agonists (endogenous substances are those produced inside the human body). Opioid substances encompass all the natural…

Sinaloa cartel: Leaders arrested: …which contributed to the growing opioid crisis in the United States.

Sinaloa cartel: Leaders arrested: …which contributed to the growing opioid crisis in the United States.

hypothalamus: Hypothalamic regulation of hormone secretion: Well-known examples are the opioids (e.g., enkephalins), so named because they are endogenous (produced in the human body) peptides (short chains of amino acids) with a strong affinity for the receptors that bind opiate drugs, such as morphine and heroin.

nervous system: Neuroactive peptides: …as eight different types of opioid receptors, but the four best-described are designated mu (μ), kappa (κ), delta (δ), and sigma (σ). The μ receptors, which readily bind morphine, are thought to mediate euphoria, respiratory depression, and physical addiction and to block pain pathways in the brain. The κ receptors…

opioid: …is referred to medically as opioid use disorder.

Opis, lost city of Babylonia, in the southern part of modern Iraq. Although the location of the ancient city has not been definitively established, it is thought to have been situated on the Tigris near the Diyala River. The city was the scene of the decisive defeat of Nabonidus, last king of

opisthobranch, any marine gastropod of the approximately 2,000 species of the subclass Opisthobranchia. These gastropods, sometimes called sea slugs and sea hares, breathe either through gills, which are located behind the heart, or through the body surface. The shell and mantle cavity are reduced

opisthobranch, any marine gastropod of the approximately 2,000 species of the subclass Opisthobranchia. These gastropods, sometimes called sea slugs and sea hares, breathe either through gills, which are located behind the heart, or through the body surface. The shell and mantle cavity are reduced

Caudata: Bones and cartilage: …ossifies, the vertebrae are termed opisthocoelous (bulged on the anterior side and depressed on the posterior side). There is one cervical vertebra with a characteristic projection called the odontoid process and two large facets for articulation with the skull. There may be from 11 (Ambystoma talpoideum) to 60 (Amphiuma) dorsal,…

hoatzin, (Opisthocomus hoazin), primitive chicken-sized bird of South American swamps, principally in the Amazon and Orinoco river basins. The young possess two large claws on each wing, a trait that has led some scientists to link the species with the fossil Archaeopteryx of the dinosaur era. The

protozoan: Annotated classification: Opisthokonta Possess a posterior flagellum at some stage in the life cycle; otherwise the posterior flagellum has been secondarily lost. Usually have flattened mitochondrial cristae. The monophyletic fungi and metazoa are classified in this group. Mesomycetozoa At least 1 life stage consisting of round cells,…

spookfish, any of about 11 species of small marine fishes constituting the family Opisthoproctidae (order Salmoniformes), with representatives in each of the major oceans. The name spookfish, or barreleye, as they are sometimes called, originates from their unusual eyes, which are pointed upward

hummingbird: …in the awlbill (Avocettula) and avocetbill (Opisthoprora).

flatworm: Annotated classification: Order Opisthorchiida Cercaria never armed; excretory pores open on margins of tail; about 700 species. There is disagreement on many aspects of the taxonomy of Platyhelminthes, especially regarding class divisions. For example, some authorities consider Monogenea to be a subclass within the class Trematoda.

fluke: The cat liver fluke, Opisthorchis felineus, which may also infest man as the final host, also requires a freshwater snail (Bithynia leachii) and a carp as its secondary intermediate hosts.

fluke: …or Oriental, liver fluke (Opisthorchis sinensis, or Clonorchis sinensis). F. hepatica causes the highly destructive “liver rot” in sheep and other domestic animals. Man may become infested with this fluke by eating uncooked vegetables.

water snake: In addition, Opisthotropis, an unusual genus made up of 20 species, lives beneath stones in mountain streams in China and Southeast Asia; it is nocturnal and feeds upon fish, adult frogs, tadpoles, and invertebrates. Females of this genus lay one to six eggs.

perciform: Annotated classification: Family Opistognathidae (jawfishes) Resemble Clinidae, but jaws large to huge, extending far past eye; dorsal fin long-based; spinous and soft portions continuous; anal fin long-based; body usually elongated, slender; eyes almost at anterior tip of head; pelvic fins below pectorals. About 78 species, mostly small, in shallow…

Martin Opitz was a German poet and literary theorist who introduced foreign literary models into German poetry and who was a pioneer in establishing a national German literature. Opitz studied at universities in Frankfurt an der Oder, Heidelberg, and Leiden, where he met the Dutch poet Daniël

Martin Opitz was a German poet and literary theorist who introduced foreign literary models into German poetry and who was a pioneer in establishing a national German literature. Opitz studied at universities in Frankfurt an der Oder, Heidelberg, and Leiden, where he met the Dutch poet Daniël

opium, narcotic drug that is obtained from the unripe seedpods of the opium poppy (Papaver somniferum), a plant of the family Papaveraceae. (See poppy.) Opium is obtained by slightly incising the seed capsules of the poppy after the plant’s flower petals have fallen. The slit seedpods exude a milky

Mouloud Mammeri: In L’Opium et le bâton (1965; “Opium and the Stick”), Mammeri constructed a story of the Algerian war of independence, attempting to give the struggle meaning in terms of the essential problem of freedom. His later works included a play, Le Banquet (1973), which dealt with…

Raymond Aron: …were L’Opium des intellectuels (1955; The Opium of the Intellectuals), which criticized left-wing conformism and the totalitarian tendencies of Marxist regimes. Aron himself became a strong supporter of the Western alliance. In La Tragédie algérienne (1957; “The Algerian Tragedy”) he voiced his support for Algerian independence, and in République impériale:…

opium poppy, (Papaver somniferum), flowering plant of the family Papaveraceae, native to Turkey. Opium, morphine, codeine, and heroin are all derived from the milky latex found in its unripe seed capsule. It is also grown for its tiny nonnarcotic ripe seeds, which are kidney-shaped and grayish blue

opium trade, in Chinese history, the traffic that developed in the 18th and 19th centuries in which Western countries, mostly Great Britain, exported opium grown in India and sold it to China. The British used the profits from the sale of opium to purchase such Chinese luxury goods as porcelain,

Opium Wars, two armed conflicts in China in the mid-19th century between the forces of Western countries and of the Qing dynasty, which ruled China from 1644 to 1911/12. The first Opium War (1839–42) was fought between China and Britain, and the second Opium War (1856–60), also known as the Arrow

braconid wasp: Major biological control species: In the Mediterranean region Opius concolor is a parasite of the olive fly (Dacus oleae), which is a destructive pest of commercial olives.

perciform: Annotated classification: Family Oplegnathidae (knifejaws) Pliocene to present. Strongly resemble Scorpidae and Kyphosidae, but incisiform teeth of young become fused in adult to form a parrotlike beak to upper and lower jaws; these fishes are not related to true parrot fishes (Scaridae); several species of shorefishes mostly in tropics…

Papua: History: …Indonesian rule, led by the Free Papua Movement (Organisasi Papua Merdeka or OPM), erupted almost immediately. The plebiscite took place in 1969, and, though the results were suspect, the area became the Indonesian province of Irian Jaya. The OPM continued to resist Indonesian rule, and violence broke out periodically. In…

Ikot Abasi, port town, Akwa Ibom state, southern Nigeria. The town lies near the mouth of the Imo (Opobo) River. Situated at a break in the mangrove swamps and rain forest of the eastern Niger River delta, it served in the 19th century as a collecting point for the trade of enslaved people. In 1870