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Die Mittelasiatische Kobra (Naja oxiana) zählt innerhalb der Familie der Giftnattern zur Gattung der Echten Kobras (Naja).
Die wissenschaftliche Erstbeschreibung von Naja oxiana wurde 1831 von Karl Eduard Eichwald durchgeführt. Er ordnete sie unter der Bezeichnung Naja naja oxiana als Unterart der Brillenschlange (Naja naja) zu.
Naja oxiana erreicht bei einem schlanken, aber dennoch kräftigem Körperbau eine Gesamtlänge von 100 bis 150 cm. Der relativ kurze Kopf setzt sich nur wenig vom Hals ab und besitzt eine rundliche Schnauze. Die Augen besitzen eine runde Pupille. Folgende pholidotischen Merkmale finden sich am Kopf: 7 Oberlippenschilde (Scutum supralabiale), von denen das dritte das höchste sowie das siebte das längste ist, ein Vorderaugenschild (Scutum präoculare) und zwei Hinteraugenschilde (Scutum postoculare). Das 3. und 4. Oberlippenschild stoßen an den Unterrand des Auges. Das Schnauzenschild (Scutum rostrale) ist etwas breiter als hoch. Den Nacken bedecken 25 Reihen, den Rücken 21 Reihen glatter Schuppen. Unterseits zeigen sich circa 108 Bauchschilde (Scutum ventrale) und 73 Unterschwanzschilde (Scutum subcaudale). Das Analschild (Scutum anale) ist nicht geteilt. Die Körperfärbung adulter Tiere ist braun oder grau, unterseits gelblich weiß und nicht gefleckt. Vor allem Jungtiere weisen rückenseitig schwarze Querbinden auf, von denen die vorderen acht auf die Bauchseite übergehen.
Wie alle Giftnattern besitzt Naja oxiana zu Giftdrüsen umgebildete Speicheldrüsen, welche über einen Giftkanal mit im vorderen Oberkiefer befindlichen, nicht beweglichen Giftzähnen verbunden sind (proteroglyphe Zahnstellung).
Die Art kommt in folgenden Ländern vor: Afghanistan, nördliches Indien, nordöstlicher Iran, Kirgistan, westliches Pakistan, Tadschikistan, Turkmenistan und Usbekistan. Die besiedelten Lebensräume (Wüsten, Halbwüsten, Gebirgsregionen) weisen heiße Sommer mit Lufttemperaturen bis 40 °C und relativ milde Winter mit durchschnittlichen Temperaturen von 10 bis 20 °C und seltenen Frösten bis −15 °C auf. Die Biotope besitzen Felsen, Geröllhalden und niedrige Vegetation. Gelegentlich dringt Naja oxiana in Gärten vor.
Die Mittelasiatische Kobra pflanzt sich durch Oviparie (eierlegend) fort. Das Gelege umfasst 8 bis 12 Eier, die circa 33 bis 38 mm in der Länge messen. In Turkmenistan erfolgt die Eiablage zwischen Juli und August, die Jungschlangen schlüpfen nach circa zwei Monaten. Zum Beutespektrum der Schlange zählen Kleinsäuger wie Mäuse, Froschlurche (z. B. Bufo viridis) sowie andere Reptilien (Echsen und andere Schlangen, z. B. Natrix tessellata), seltener auch Vögel. Die Mittelasiatische Kobra lebt überwiegend auf dem Boden, klettert für die Beutesuche jedoch auch in Gebüsch und Bäumen. Zumeist ist das Tier tagaktiv und bodenbewohnend. Über die kalte Jahreszeit hält die Art eine etwa sechsmonatige Winterruhe. Sie ist witterungsabhängig sowohl tag- als auch nachtaktiv. Bei Bedrohung richtet sie den Vorderkörper auf und stellt durch Spreizung der vorderen Rippen den für Kobras charakteristischen Hut auf. Naja oxiana verteidigt sich durch Giftbisse, nicht jedoch durch Giftspeien.
Das Toxingemisch der Mittelasiatischen Kobra ist äußerst potent, der Giftbiss ist für den Menschen lebensbedrohlich. Das Gift enthält in erster Linie postsynaptische Neurotoxine (z. B. Short Neurotoxin 1, ein Drei-Finger-Toxin), die als Antagonisten an peripheren Nikotinrezeptoren wirken,[1] sowie Zytotoxine wie Zytotoxin 2 (ebenfalls ein Drei-Finger-Toxin), welches mit der Biomembran von Zellen interagiert und zur Zytolyse führt.[2]
Mit einem Giftbiss können nach Latifi et al. (1985) circa 100 (± 25) mg Giftgemisch (Trockengewicht) abgegeben werden. Nach einem Biss beim Menschen können unspezifische Allgemeinsymptome (z. B. Kopfschmerz, Übelkeit, Emesis, Abdominalschmerzen, Diarrhoe, Schwindel, Schock, Krämpfe) auftreten. Lokal können Schmerzen, Schwellung, Ödem, Blasenbildung und Nekrose auftreten. Die Neurotoxine bewirken eine fortschreitende Lähmung, die sich anfänglich durch Ptosis bemerkbar macht und bis zur vollständigen Paralyse führen kann. Der Tod tritt durch Atemlähmung ein.[3]
Folgende Antivenine stehen zur Verfügung:[3]
Naja oxiana ist im Anhang B der EU-Artenschutzverordnung gelistet, die Haltung in Gefangenschaft ist demnach meldepflichtig.
Die Mittelasiatische Kobra (Naja oxiana) zählt innerhalb der Familie der Giftnattern zur Gattung der Echten Kobras (Naja).
The Caspian cobra (Naja oxiana), also called the Central Asian cobra, ladle snake,[5] Oxus cobra, or Russian cobra, is a species of venomous snake in the family Elapidae. The species is endemic to Central Asia. Described by Karl Eichwald in 1831, it was for many years considered a subspecies of the Indian cobra until genetic analysis revealed it to be a distinct species.
Baltic German naturalist Karl Eichwald described the Caspian cobra originally as Tomyris oxiana in 1831.[6] Russian naturalist Alexander Strauch placed it in the genus Naja in 1868. The generic name naja is a Latinisation of the Sanskrit word nāgá (नाग) meaning "cobra". The specific epithet oxiana is derived from the word Ōxus in Latin or Ὦξος (Ôxos) in Greek,[7] and refers to the ancient name of the river Amu Darya which flows along Afghanistan`s northern border separating it from Tajikistan and Uzbekistan before turning northwest into Turkmenistan and flows from there into the southern remnants of the Aral Sea in Central Asia (Transoxiana), where this species occurs. For most of the twentieth century, all Asiatic cobras were considered to be subspecies of the Indian cobra (Naja naja); during this period, the subspecific names N. naja oxiana and N. naja caeca were applied to plain-scaled populations of N. naja from the north of India as well as populations corresponding to the Caspian cobra. Highly variable coloration and size within individual species made classification difficult until the advent of genetic analysis.[8]
A mitochondrial DNA study of Asiatic cobras in the subgenus Naja showed the Caspian cobra diverged from a lineage that gave rise to the monocled cobra (Naja kaouthia) and the Andaman cobra (Naja sagittifera) around 3.21 million years ago. The species itself appears to be genetically homogeneous despite population separation caused by the Hindu Kush mountains; this suggests a recent rapid range expansion.[9]
Naja (Naja) (Afronaja) (Boulengerina)Naja (Boulengerina) multifasciata
Naja (Boulengerina) guineensis
Naja (Boulengerina) peroescobari
Naja (Boulengerina) melanoleuca
(Uraeus)Naja oxiana is medium in length, a heavy-bodied snake with long cervical ribs capable of expansion to form a hood. Anteriorly, the body is depressed dorsoventrally, and posteriorly it is subcylindrical. This species is similar in size to Naja naja, averaging about 1 to 1.4 m (3.3 to 4.6 ft)[10][11] in total length (including tail) and rarely reaches lengths over 1.7 m (5.6 ft).[10][12] The head is elliptical, depressed, and slightly distinct from the neck, with a short, rounded snout and large nostrils. The eye is medium in size with a round pupil. The dorsal scales are smooth and strongly oblique, with the outer two or three scale rows larger than the remainder.[13] The hood of N. oxiana has an elongate, gradually tapering shape in contrast to the more ovoid hoods of some other Naja species (Naja naja or Naja kaouthia).[11] Juveniles tend to be pale, with a faded appearance. Juveniles have noticeable dark and light cross-bands of approximately equal width around the body. Adults of this species are completely light to chocolate brown or yellowish, with some specimens retaining traces of juvenile banding, especially the first few dark ventral bands. This species has no hood mark and no lateral throat spots.[12]
Confusions may exist with the Indian cobra (Naja naja), as specimens without a hood mark are usually confused with this species, and these two species coexist in Pakistan and northern India. They're also both the only true non-spitting cobras in Asia.[14] The Caspian cobra (Naja oxiana) is never fully black, although some specimens may be quite dark. The Caspian cobra (N. oxiana) normally has several dark bands under the throat, whereas in the black phase of the Indian cobra (N. naja) from Pakistan, almost the entire throat is black.[15] The hood has an elongate, gradually tapering shape in contrast to the more ovoid hoods of some other Naja species (Naja naja or Naja kaouthia).[11]
The number and pattern of scales on a snake's body are a key element of identification to species level.[16] Naja oxiana has 23 to 27 (usually 25) dorsal scale rows at the hood, 19–23 (usually 21) just ahead of midbody, 191–210 ventrals, and 57–71 paired subcaudals; cuneate scales (small angular scales between the labials) are often absent.[12]
Naja oxiana occurs in the Transcaspian region. It is found throughout Turkmenistan, Uzbekistan, Kyrgyzstan, southwestern Tajikistan, the Fergana Valley, north and east Afghanistan, northeastern Iran. In Iran, it occurs from East Azerbaijan Province, southern half of Ardabil Province to the Provinces of Zanjan and Tehran all the way to the eastern half of both Isfahan and Yazd Provinces, as well the northeastern parts of Kerman Province, northern part of Sistan and Baluchistan Province, throughout the Provinces of Semnan, Mazandaran, and Golestan the entire former Province of Khorasan, which was split into three separate provinces post-2004). Although this species is found throughout much of Pakistan, from Balochistan and Sindh to Gilgit-Baltistan and Azad Kashmir,[13] it is far more common in the northern half of Pakistan. This species has also been observed in far northwest India in Jammu and Kashmir (union territory) and also been observed in the state of Himachal Pradesh. It's also highly suspected to occur in Ladakh,[12] and in the Indian state of Punjab.[13][12] There is also anecdotal evidence of it ranging as far north as Kazakhstan's southern border with Uzbekistan, according to Brian Hayes, a biochemical engineer with the United States Threat Reduction Agency. Hayes led an expedition to Vozrozhdeniye Island in the Aral Sea in the summer of 2002 to bury anthrax on the island, which is located in the Aral Sea and is split between Uzbekistan and Kazakhstan, with the northern half of the island belonging to Kazakhstan. Mr. Hayes mentioned a 2.4 m (7.9 ft) long cobra that was observed and shot near the tents where the staff lived. “In all, we had run-ins with about 25 poisonous snakes”.[17] The only "cobra” species which occurs in this region is Naja oxiana, so any “cobra” observed in Kazakhstan would likely be of this species.
Naja oxiana is often found in arid and semiarid, rocky or stony, shrub or scrub covered foothills[13] at elevations up to about 3,000 m (9,800 ft) above sea level. This is also the westernmost species of Asiatic cobra.[18]
Naja oxiana tends to avoid humans as much as it can, but it can become fiercely defensive when threatened or cornered, and even juveniles tend to be very aggressive. When cornered and provoked, it is liable to spread its hood, hiss, sway from side to side and strike repeatedly; however, it can not spit venom. This terrestrial species is mainly diurnal, but it may be crepuscular and nocturnal in some parts of its range during the hottest month (July). Caspian cobras are good climbers, and able swimmers. The Caspian cobra is often found in water and seldom found too far away from it.[13][11] Quick-moving and agile, this species lives in holes in embankments or trees.[18]
The Caspian Cobra feeds mostly on small mammals, amphibians, occasionally fish, birds and their eggs. It also reportedly feeds on other snakes.[19][13][11]
The Caspian cobra is considered to be the most venomous species of cobra in the world. Several different toxinological studies suggest this, including one particular study reported in the Indian Journal of Experimental Biology in 1992.[20] A study analyzing the toxic fractions of Naja oxiana venom from Iran indicated that toxic fractions constituted 78% by weight of crude venom of this species,[21] similar to Naja naja.[22] The toxic fractions were composed of three protein families, among which the 3FTs was dominant, similar to all other Naja species. The venom of N. oxiana was rich in short neurotoxins, which make up the majority of crude venom.[21] A number of small nonenzymatic proteins are found in the venom, including neurotoxins and members of the cytotoxin family,[23] which have been shown to cause cell death through damage to lysosomes.[24]
In addition to nonenzymatic proteins, the venom also contains nucleases, which cause tissue damage at the site of the bite and may also potentiate systemic toxicity by releasing free purines in situ.[25] A ribonuclease isolated and purified from Caspian cobra venom, ribonuclease V1, is commonly used as a laboratory reagent in molecular biology experiments due to its unusual ability to break down structured RNA.[26]
N. oxiana is one of the most dangerous snakes belonging to the elapidae family. Two main toxins as well as a number of minor components and three basic polypeptides similar to cardiotoxins (CTXs) and cytotoxins were isolated from the crude venom of this species, with acute effects on cardiac system during the first few hours post-envenomation. There are a few case reports of acute myocardial infarction (MI) following bites from elapids. At least one case of myocardial infarction following a bite from a Caspian cobra is recorded.[27]
Naja oxiana is regarded as the most dangerous snake in Central Asia and is one of the venomous snakes with a high mortality rate.[28] It is one of the most dangerous elapid species in the world.[27] A bite from this species will cause severe pain and swelling at the site of the bite, along with rapid onset of prominent neurotoxicity. Weakness, drowsiness, ataxia, hypotension, and paralysis of throat and limbs may appear in less than one hour after the bite. In a study, the first signs and symptoms of envenomation appeared within 15 minutes post-envenomation. Without medical treatment, symptoms rapidly worsen and death can occur soon after a bite due to respiratory failure.[18] As with all species of cobra, there is great variation in venom toxicity and composition based on diet and geographical location. Venom toxicity is highest (least lethal) among specimens in the eastern parts of their geographical range (Indian and Pakistani specimens) with a value of around 0.2 mg/kg. Specimens from Iran, Uzbekistan, northeastern Afghanistan, and Turkmenistan can have considerably more potent venoms. Onset of symptoms are rapid and are extremely painful. Without treatment, death is likely and depending on the nature of the bite, the potency of the venom and the amount, death can occur in as little as 45 minutes or may be prolonged for up to 24 hours.[27]
According to a 2019 study by Kazemi-Lomedasht et al., the murine LD50 via subcutaneous injection value for Naja oxiana (Iranian specimens) was estimated to be 0.14 mg/kg (0.067-0.21 mg/kg)[28] more potent than the sympatric Pakistani Naja naja karachiensis (0.22 mg/kg), the Thai Naja kaouthia (0.2 mg/kg), and Naja philippinensis at 0.18 mg/kg (0.11-0.3 mg/kg)[29] An older study by Zug et al listed a LD50 value of 0.2 mg/kg from Pakistani and Indian specimens.[30] Average venom yield per bite for this species is between 75 and 125 mg (dry weight),[13] while in other parts of its distribution venom yield average is between 150 and 225 mg (dry weight).[28] The highest single bite yields are between 590[31] and 784 mg (dry weight).[28] The crude venom of N. oxiana has a lowest published lethal dose (LCLo) of 0.005 mg/kg, the lowest among all cobra species, derived from an individual case of poisoning by intracerebroventricular injection.[32]
Between 1979 and 1987, 136 confirmed bites were attributed to this species in the former Soviet Union. Of the 136, 121 received antivenom, and only 8 died (6.6%). Of the 15 who did not receive antivenom, 11 died (untreated mortality rate of 73%).[33][34] In Iran, where the Caspian cobra is widespread, it is responsible for the highest number of deaths due to snakebite in the country. The Levant viper, Saw-scaled viper, and the Persian horned viper are responsible for more snakebite incidents, but they have a lower mortality rate compared to N. oxiana. Multiplying habitat suitability models of the four snakes showed that the northeast of Iran (west of Khorasan-e-Razavi province) has the highest snakebite risk in the country. In addition, villages that were at risk of envenoming from the four snakes were identified. Results revealed that 51,112 villages are at risk of envenoming from M. lebetinus (Levant viper), 30,339 from E. carinatus (saw-scaled viper), 51,657 from P. persicus (Persian horned viper) and 12,124 from N. oxiana (Caspian cobra). A study reported 53,787 cases of bites by venomous snakes between 2002 and 2011 in Iran, with the highest rate of snakebite incidents being found in provinces in the south and southwest of Iran.[35] Out of the 53,787 cases of snake bites which were reported to medical centers in Iran, only 118 were correctly identified as bites by this species. In total there were 67 deaths, 51 of which were due to N. oxiana. Out of 51 bites, 46 didn't receive medical treatment. One 10 year old male died en route to the closest hospital ~35 minutes post-envenomation. Five were treated with antivenom, but succumbed to the venom regardless of the fact (~7% mortality despite treatment). Untreated mortality rates seem to be particularly high for a species within the genus Naja, at around ~80%.[35][36][5] In Pakistan, it is responsible for high rates of snakebites that result in mortality.[18] Reliable figures on incidence, morbidity and mortality are limited but almost 40,000 biting cases are reported annually which result up to 8,200 fatalities in one study. An estimates of annual mortality rate in Pakistan is around 1.9 per 100,000 population. In one survey, it was reported that out of 5,337 envenomed patients, 57% were cobra victims and the remaining rest of 35% were bitten by kraits and vipers. Of the 5,337 envenomed patients, there were 3,064 cobra (N. naja and N. oxiana) victims. Out of the 3,064 bitten by cobras (841 correctly identified as N. naja, and 384 were correctly identified as N. oxiana). There were 78 untreated case, of which 64 were fatal (82%), much higher than untreated cases for N. naja (33.6%).[31][37] A woman bitten by this species in northwestern Pakistan suffered prominent neurotoxicity and died while en route to the closest hospital nearly 50 minutes after envenomation (death occurred 45–50 minutes post envenomation).[36] Antivenom is not as effective for envenomation by this species as it is for other Asiatic cobras within the same region, like the Indian cobra (N. naja), and due to the dangerous toxicity of this species' venom, massive amounts of antivenom are often required for patients. As a result, a monovalent antivenom serum is being developed by the Razi Vaccine and Serum Research Institute in Iran. Response to treatment with antivenom is generally poor among patients, so mechanical ventilation and endotracheal intubation is required. As a result, mortality among those treated for N. oxiana envenomation is still relatively high (up to 30%) compared to all other species of cobra (<1%).[31]
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{{cite journal}}: CS1 maint: multiple names: authors list (link) The Caspian cobra (Naja oxiana), also called the Central Asian cobra, ladle snake, Oxus cobra, or Russian cobra, is a species of venomous snake in the family Elapidae. The species is endemic to Central Asia. Described by Karl Eichwald in 1831, it was for many years considered a subspecies of the Indian cobra until genetic analysis revealed it to be a distinct species.
La cobra de Asia Central (Naja oxiana) fue descripta, por vez primera, por Eichwald, en 1831, clasificándola dentro del género Tomyris, otorgándole el binomial Tomyris oxiana. Sin embargo, en 1868, entendiendo que el trabajo de Eichwald era erróneo, Strauch la ubica en el género Naja bajo la clasificación Naja oxiana. Más adelante, otros zoólogos y herpetólogos, discienten con el trabajo de Strauch y varían su clasificación, aunque sin retirarla del género; así, Boulenguer, la entiende como una subespecie de la Naja tripudians, y la denomina como Naja tripudians caeca (1896), mientras que, por su parte, Stejneger la entiende como una subespecie de la Naja naja, clasificándola como Naja naja oxiana (1907).En el presente, y a partir de la reclasificación realizada por Welch a finales del siglo XX, adquiere nuevamente el rango de especie con el nombre de Naja oxiana, dado originalmente por Strauch.
Esta especie de serpiente alcanza una longitud de entre 1 metro a 1.50, dificultosamente sobrepasando tales tallas. La tonalidad del cuerpo es de un pardo claro, distribuido de manera uniforme uniforme, sin embargo, se han encontrado individuos que presentan colores café, chocolate e, incluso, amarillento. Algunos individuos, en casos bastante infrecuentes, conservan la coloración de su etapa juvenil. La capucha, característica de todas las especies de cobra, no presenta manchas ni marcas de ningún tipo, como si observamos en otras Naja, como la más conocida Naja naja.
Los ejemplares jóvenes poseen tonalidades extremadamente pálidas, y comparándolos con los individuos en fase adulta, son mucho menos atractivos.
El área de dispersión natural de la Naja oxiana se extiende por Uzbekistán, Tayikistán, Turkmenistán, Kirguistán, la Cachemira pakistaní, Afganistán, India e Irán.
Esta especie es de una alta toxicidad, siendo su mordida responsable de múltiples muertes humanas en el territorio donde se encuentran dispersas.
Datos: Q2349137
Multimedia:
Especies: Naja oxiana
Naja oxiana Naja generoko animalia da. Narrastien barruko Elapidae familian sailkatuta dago.
Naja oxiana Naja generoko animalia da. Narrastien barruko Elapidae familian sailkatuta dago.
Naja oxiana est une espèce de serpents de la famille des Elapidae[1].
C'est un cobra assez petit à moyen, dont la longueur tourne autour d'un mètre en moyenne, et atteignant jusqu'à 1,5 m. Sa coloration est souvent constituée de bandes assez sombres sur un fond plus clair, s'atténuant souvent avec l'âge sauf au niveau du cou. Certains spécimens ont une coloration plus uniforme claire ou sombre. Sa coiffe est moins large que celle du cobra indien, avec lequel il peut cohabiter dans le sud-est de son aire.
Cette espèce se rencontre sans le sud de l'Asie centrale : en Iran, au Turkménistan, en Ouzbékistan, au Kirghizistan, au Tadjikistan, en Afghanistan, et au nord du Pakistan et de l'Inde[1].
Ce serpent vit en partie dans des régions tempérées. Les hivers peuvent être assez rudes dans certaines parties de son aire, ce qui le conduit à hiverner durant la mauvaise saison. C'est la seule espèce du genre Naja vivant en dehors des climats tropicaux ou subtropicaux. Ses habitats sont variés. Il habite surtout des régions plus ou moins arides avec une végétation herbeuse ou buissonnante clairsemée, des zones rocheuses, des prairies ou des boisements clairs, mais au sein de ces régions il est aussi fréquemment présent aux abords des zones humides ainsi que dans les zones cultivées. On le trouve jusqu'à 3 000 m d'altitude.
Naja oxiana fait partie des serpents les plus venimeux du monde. Parmi toutes les espèces du genre Naja d'Asie et d'Afrique, il est celle dont le venin est le plus puissant.
La DL 50 en injection sous-cutanée chez la souris est en moyenne de 0,18 mg/kg (variant de 0,10 mg/kg à 0,26 mg/kg selon les études)[2], tandis que la DL 50 en injection intraveineuse varie de 0,037 mg/kg[3] à 0,078 mg/kg[4]. Or la quantité de venin qu'il injecte en une morsure varie de 75 à 125 mg (poids sec)[5].
Le taux de mortalité des personnes mordues sans prise en charge médicale est d'environ 73 %. La part de survivants sans traitement s'explique avant tout par les morsures sèches assez fréquentes (cas où le serpent n'a pas eu le temps d'injecter son venin). C'est un venin essentiellement neurotoxique. Ses effets sont rapides et la mort peut survenir en moins d'une heure après la morsure. Cependant la prise en charge médicale rapide et le traitement au moyen de sérums antivenimeux permettent de réduire fortement le taux de mortalité des personnes mordues.
Il cobra del Caspio (Naja oxiana (Eichwald, 1831)), noto anche come cobra centroasiatico, è un serpente appartenente alla famiglia degli Elapidi[2].
Serpente di dimensioni medio-grandi, presenta una lunghezza che si aggira intorno al metro e solo in casi molto rari supera il metro e mezzo; sono stati documentati, tuttavia, esemplari che hanno raggiunto i 190 centimetri. Ha corpo tozzo, come quello di molti altri cobra, compresso sull'asse dorso-ventrale e cilindrico nella parte posteriore. Come gli altri cobra, possiede lunghe costole nella parte anteriore che, allargandosi, formano il caratteristico cappuccio. Gli adulti hanno una colorazione uniforme, sulle varie tonalità del marrone, dall'ocra al color cioccolato, e non presentano alcun segno distintivo, quali disegni sul cappuccio o macchie laterali sulla gola. I giovani, al contrario, presentano strisce molto evidenti, sia sul dorso che sul ventre. Queste schiariscono molto con la crescita dell'animale, fino a rimanere appena visibili solamente in prossimità della zona ventrale. Il ventre è molto chiaro, quasi sempre color crema, e presenta talvolta delle macchie o, come abbiamo appena detto, delle strisce. La testa ha forma ellittica, depressa e poco distinta dal corpo, con muso corto e arrotondato con narici ampie. Gli occhi sono di medie dimensioni, con pupille rotonde. I denti veleniferi misurano in media 5,5 mm. Le squame sono lisce e fortemente oblique, di colore più chiaro ai bordi che al centro.
In linea generale possiamo affermare che ricorda molto nell'aspetto il cobra dagli occhiali (Naja naja), dato che quest'ultimo può non presentare il classico disegno sul cappuccio. In passato, infatti, il cobra del Caspio veniva considerato una semplice sottospecie di quest'ultimo. Nelle zone in cui gli areali delle due specie si sovrappongono, in Pakistan e India, esse vengono spesso confuse[3].
È presente in Afghanistan, India settentrionale, Iran nord-orientale, Kirghizistan, Pakistan occidentale, Tagikistan, Turkmenistan e Uzbekistan. Gli habitat in cui vive (deserti, semi-deserti e regioni montuose) sono caratterizzati da estati torride con temperature che possono raggiungere i 40 °C e da inverni relativamente miti, con temperature medie comprese tra 10 e 20 °C, ma che raramente possono precipitare a -15 °C. Si incontra principalmente su terreni ricoperti da rocce, ghiaioni e bassa vegetazione. Occasionalmente, penetra nei giardini.
Il cobra del Caspio è prevalentemente diurno e terricolo. In genere è attivo la mattina presto, ma durante i mesi più caldi dell'anno, come luglio e agosto, può farsi crepuscolare. È un animale agile e veloce e, sebbene viva quasi sempre sul terreno, è un buon arrampicatore. È inoltre un ottimo nuotatore, e non è affatto raro vederlo nell'acqua. Generalmente trova riparo sugli alberi o in buche del terreno. Creatura particolarmente aggressiva e suscettibile, soprattutto gli esemplari più giovani, cerca in genere di evitare gli esseri umani, tanto da preferire la fuga all'attacco diretto, ma nel caso venga messo alle strette apre il cappuccio ed emette un sibilo, oscillando con il corpo da un lato all'altro, prima di mordere, anche ripetutamente. Pur essendo un abile predatore, il cobra del Caspio, specialmente da giovane, viene a sua volta predato da manguste, altri serpenti e diverse specie di rapaci[3].
Si nutre di piccoli mammiferi, specialmente roditori, anfibi, uccelli, uova e pesci. La dieta dei giovani, invece, comprende solamente rane, rospi e lucertole[3].
Il cobra del Caspio è considerato il più velenoso tra tutti i cobra. Il suo veleno neurotossico e citotossico, infatti, è piuttosto potente, con un LD50 sottocutaneo pari a 0,45 mg/kg. Il serpente è in grado di iniettare, con un solo morso, da 75 a 125 mg di veleno, arrivando, in casi eccezionali, fino a 300 mg. Il veleno provoca inizialmente un forte dolore e un gonfiore esteso nella zona del morso, sulla quale compaiono poi lividi, vesciche e necrosi grave o moderata dei tessuti. In seguito compaiono mal di testa e/o vertigini, nausea e vomito, dolore addominale, diarrea, debolezza e sonnolenza, ipotensione, atassia, paralisi della gola e/o degli arti, convulsioni e collasso. Tutti i sintomi peggiorano molto velocemente e, in assenza di un intervento medico, può sopraggiungere la morte per insufficienza respiratoria. Il tasso di mortalità, in assenza di cure, è molto alto, con valori compresi tra il 70 e il 75%. Contro il veleno del cobra del Caspio, tuttavia, esistono due antidoti polivalenti e uno monovalente, che devono essere somministati per via endovenosa in grosse quantità[3].
Non abbiamo molte notizie riguardanti la riproduzione del cobra del Caspio, ma come tutti gli altri cobra è oviparo: la femmina depone da 6 a 19 uova, di circa 33-438 cm di lunghezza. In Turkmenistan la deposizione avviene tra luglio e agosto, e i piccoli nascono dopo circa due mesi. Questi ultimi sono indipendenti e già velenosi a partire dalla nascita[3].
La deforestazione per creare pascoli, costruire case e ricavare legna da ardere sta lentamente facendo scomparire l'habitat naturale e le prede di questi animali, ed è sempre più frequente incontrare questi serpenti nelle aree urbane, in cui si spingono alla disperata ricerca di cibo. Viene inoltre ucciso deliberatamente per la sua pelle e per il suo uso nella medicina popolare, nonché catturato anche per essere usato nei combattimenti con le manguste e, dopo avergli strappato i denti veleniferi, negli spettacoli degli incantatori di serpenti. Classificato come «specie in pericolo» (Endangered) dal 1986 al 1990, attualmente gli esperti della IUCN ritengono di avere dati insufficienti per poterne valutare il rischio di estinzione. È comunque protetto in tutte le riserve naturali del Tagikistan, del Turkmenistan e dell'Uzbekistan[3].
Il cobra del Caspio (Naja oxiana (Eichwald, 1831)), noto anche come cobra centroasiatico, è un serpente appartenente alla famiglia degli Elapidi.
Vidurinės Azijos (lot. Naja oxiana) – aspidų (Elapidae) šeimos nuodingųjų gyvačių rūšis, viena nuodingiausių kobrų. Paplitusi Vidurinėje Azijoje.
Gyvatės ilgis siekia iki 2 m ir daugiau, paprastai būna 160-180 cm ilgio. Suaugusios gyvatės kūno viršutinė dalis būna nuo šviesiai alyvinės iki tamsiai rudos spalvos, papilvė šviesi, gelsvos spalvos. Jaunoms kobroms būdingi ryškūs tamsūs skersiniai ratilai pilvo srityje. Kobrai bręstant bendras spalvų tonas darosi tamsesnis. Skersiniai dryžiai blanksta ir darosi platesni, papilvėje jie išnyksta, vietoje jų atsiranda dėmės. Akių vyzdžiai apvalūs, žvynai lygūs. Suerzinta gyvatė pakyla į viršų apie trečdalį savo ūgio, išpūsdama kaklo gobtuvą.
Vidurinės Azijos kobra gyvena priekalnėse, neaukštuose kalnuose, upių slėniuose, tarpekliuose, ant šlaitų, krūmynuose, soduose, apleistuose statiniuose. Dažnai sutinkamos upių pakrantėse, nuklysta į smėlio dykumas prie smiltpelių kolonijų, kalnuose pakyla į 2000 m aukštį virš jūros lygio. Aktyvi dieną ir naktį. Minta smulkiais žinduoliais (apie 15-20 % raciono), varliagyviais (40 %; ypač daug pagauna žaliųjų rupūžių ar ežerinių varlių, priklausomai nuo gyvenamosios vietos), ropliais, tame tarpe kitomis gyvatėmis (30-35 %), paukščiais (5-10 %) ir jų kiaušiniais.
Patelės liepą padeda 6-19 pailgų kiaušinių, 40-54 mm ilgio, 12-19 g svorio. Jaunikliai išsilupa rugpjūčio antroje pusėje – rugsėjo mėn. Jų ilgis siekia 31-39 mm. Subręsta ketvirtaisiais gyvenimo metais.
Vidurinės Azijos kobros įgėlimas žmogaus ar gyvulio organizme pasižymi stipriu neurotoksinų poveikiu. Sušvirkšti nuodai sukelia vangumą, galvos svaigimą, netrukus paralyžiuojami kvėpavimas ir raumenys, ištinka mirtis. Šios kobros nuodai naudojami medicininių preparatų gamyboje, eksperimentinėje biologijoje – tuo tikslu jos yra laikomos specialiuose serpentariumuose.
Vidurinės Azijos (lot. Naja oxiana) – aspidų (Elapidae) šeimos nuodingųjų gyvačių rūšis, viena nuodingiausių kobrų. Paplitusi Vidurinėje Azijoje.
Gyvatės ilgis siekia iki 2 m ir daugiau, paprastai būna 160-180 cm ilgio. Suaugusios gyvatės kūno viršutinė dalis būna nuo šviesiai alyvinės iki tamsiai rudos spalvos, papilvė šviesi, gelsvos spalvos. Jaunoms kobroms būdingi ryškūs tamsūs skersiniai ratilai pilvo srityje. Kobrai bręstant bendras spalvų tonas darosi tamsesnis. Skersiniai dryžiai blanksta ir darosi platesni, papilvėje jie išnyksta, vietoje jų atsiranda dėmės. Akių vyzdžiai apvalūs, žvynai lygūs. Suerzinta gyvatė pakyla į viršų apie trečdalį savo ūgio, išpūsdama kaklo gobtuvą.
Multimedia w Wikimedia Commons Kobra środkowoazjatycka (Naja oxiana) – gatunek jadowitego węża z rodziny zdradnicowatych (Elapidae). Występuje na terenach od Morza Kaspijskiego, aż po północne Indie[4]. Jako jedna z dwóch kobr azjatyckich nie potrafi pluć jadem.
Opis: osiąga długość do 1,7 m; ciemnożółta lub jasnobrązowa.
Kobra środkowoazjatycka (Naja oxiana) – gatunek jadowitego węża z rodziny zdradnicowatych (Elapidae). Występuje na terenach od Morza Kaspijskiego, aż po północne Indie. Jako jedna z dwóch kobr azjatyckich nie potrafi pluć jadem.
Opis: osiąga długość do 1,7 m; ciemnożółta lub jasnobrązowa.
Naja oxiana[2] este o specie de șerpi din genul Naja, familia Elapidae, descrisă de Eichwald 1831.[3][4][1] Conform Catalogue of Life specia Naja oxiana nu are subspecii cunoscute.[3]
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Acest articol referitor la o reptilă este un ciot. Puteți ajuta Wikipedia prin completarea sa. Naja oxiana este o specie de șerpi din genul Naja, familia Elapidae, descrisă de Eichwald 1831. Conform Catalogue of Life specia Naja oxiana nu are subspecii cunoscute.
Naja oxiana là một loài rắn trong họ Rắn hổ. Loài này được Eichwald mô tả khoa học đầu tiên năm 1831.[3]
Naja oxiana là một loài rắn trong họ Rắn hổ. Loài này được Eichwald mô tả khoa học đầu tiên năm 1831.
