రక్త పింజరి
రక్తపింజరి పాము జాతులు చాలా ఆగ్నేయాసియా ప్రాంతాలు, భారత ఉపఖండం అంతటా మరియు ఆసియాలో దక్షిణ చైనా నుండి టైవాన్ వరకు విస్తరించి ఉన్నాయి. దీనిని కాటుక రేకుల పాము అని కూడా పిలుస్తారు. దాని ప్రకోప స్వభావం కారణంగా ఏ ఇతర విషసర్పాల కంటే కూడా ఎక్కువ మానవ మరణాలకు బాధ్యత వహిస్తుంది. దాదాపు అన్ని భారతీయ పాముకాటు మరణాలకు కారణమైన నాలుగు విష స్రావము గల సర్పాలలో ఇదీ ఒకటి.
ఈ పాము గరిష్ఠంగా 166 సెం.మీ. (5.5 అడుగులు) పొడవు పెరుగుతుంది. అయితే సగటు పొడవు, ప్రధాన భూభాగంలో 120 గురించి సెం.మీ. (4 అడుగులు). అనేక ఇతర విష సర్పాలు కంటే ఇది మరింత సన్నగా నిర్మించబడింది.దిత్మార్స్ (1937) "సరైన పరిమాణపు వయోజన నమూనాను" కొరకు ఈ క్రింది కొలతలు నివేదించారు.
తల చదునుగా, త్రిభుజాకారంగా మెడ నుండి వైవిధ్యంగా ఉంటుంది.జంతువుల ముట్టె భాగము సమీప మరియు పెరిగింది, మొద్దుబారిన ఉంది. నాసికా రంధ్రాల పెద్ద, సింగిల్ నాసికా ఎత్తున మధ్యలో, పెద్ద ఉన్నాయి. నాసికా దిగువ అంచు nasorostral తాకినప్పుడు. supranasal బలమైన చంద్రవంక ఆకారంలో మరియు nasorostral anteriorly నుండి నాసికా విడదీస్తుంది. ఇది ఎక్కువగాగా rostral. విస్తృత [2]
తల కిరీటం సక్రమంగా, గట్టిగా విచ్ఛిన్న ప్రమాణాలతో కప్పబడి ఉంటుంది. supraocular ప్రమాణాల సంకుచితమైన, సింగిల్, మరియు తల మీదుగా 6-9 ప్రమాణాల ద్వారా వేరు. కళ్ళు పసుపు లేదా బంగారుతో flecked, పెద్దవి, మరియు ప్రతి 10-15 circumorbital ప్రమాణాల చుట్టుముట్టి ఉంది. గణనీయంగా పెద్ద 4, 5 వీటిలో 10-12 supralabials ఉన్నాయి. కంటి suboculars యొక్క 3-4 వరుసలు ద్వారా supralabials నుండి వేరుచేయబడి ఉంటుంది. గడ్డం షీల్డ్స్, ముఖ్యంగా విస్తరించి ఉన్న ముందు జత రెండు జతల ఉన్నాయి. రెండు పై దవడ యొక్క ఎముకలు ఒక సమయంలో కోరలు అత్యంత ఐదు లేదా ఆరు జతల వద్ద కనీసం రెండు మరియు మద్దతు:.. మొదటి ఉత్సాహంగా ఉన్నాయి మరియు మిగిలిన స్థానంలో [2] కోరలు సగటు స్పెసిమెన్ లో 16 mm పొడవు సాధించడానికి [13]
శరీర, స్థూపాకారకు సమీప ఇది అడ్డుకోత బలిసిన ఉంది. మెదడు ప్రమాణాల గట్టిగా keeled ఉంటాయి; మాత్రమే తక్కువ వరుస నునుపుగా ఉంటుంది. మధ్య శరీరం, మెదడు ప్రమాణాల సంఖ్య 27-33. ముందువైపు ప్రమాణాల సంఖ్య 153-180. ఆసన ప్లేట్ విభజించబడింది లేదు. తోక చిన్నదిగా ఉంది - మొత్తం శరీరం పొడవు ఇది 14% -. జత subcaudals 41-68 అంకెలతో [2]
రంగు నమూనా దాని శరీరం యొక్క పొడవు అమలు ఆ ముదురు గోధుమ రంగు మచ్చలు మూడు సిరీస్ తో లోతైన పసుపు, తాన్ లేదా గోధుమ గ్రౌండ్ రంగు, ఉంటుంది. ఈ మచ్చలు ప్రతి దాని చుట్టూ ఒక నల్లని రింగ్ ఉంది, ఇది బాహ్య సరిహద్దు తెలుపు లేదా పసుపు ఒక చట్రంతో తీవ్రమైంది ఉంది. మెదడు మచ్చలు, సైడ్ మచ్చలు విభజించు మే అయితే ఇది సాధారణంగా సంఖ్య 23-30, కలిసి పెరగడం ఉండవచ్చు. తల ఒక pinkish, సాల్మన్ లేదా బ్రౌనిష్ వి లేదా జంతువుల ముట్టె భాగము వైపు ఒక శిఖరాగ్ర ఆ రూపాలు X నమూనా కలిసి, ప్రత్యేకమైన కృష్ణ అతుకులు, ప్రతి ఆలయం న ఒక ఒక జత చేసింది. కంటి వెనుక, గులాబీ లేదా బ్ తెలుపు అంశాన్ని ఒక చీకటి పరంపర, ఉంది. ఉదరకుహరము తరచుగా కృష్ణ మచ్చలు ఒక సక్రమంగా పరిక్షేపం తో, తెలుపు whitish, పసుపు లేదా pinkish ఉంది.Found in Pakistan, India, Sri Lanka, Bangladesh, Nepal, Myanmar, Thailand, Cambodia, China (Guangxi, Guangdong), Taiwan and Indonesia (Endeh, Flores, east Java, Komodo, Lomblen Islands). The type locality is listed as "India". More specifically, this would be the Coromandel Coast, by inference of Russell (1796).
Brown (1973) mentions that it can also found in Vietnam, Laos and on the Indonesian island of Sumatra. Ditmars (1937) reportedly received a specimen from Sumatra as well. However, the distribution of this species in the Indonesian archipelago is still being elucidated.
Within its range it can be very common in some areas, but scarce in others. In India, is abundant in Punjab, very common along the West Coast and its hills, in southern India and up to Bengal. It is uncommon to rare in the Ganga valley, northern Bengal and Assam. It is prevalent in Myanmar.
It is not restricted to any particular habitat, but does tend to avoid dense forests. The snake is mostly found in open, grassy or bushy areas, but may also be found in second growth forests (scrub jungles), on forested plantations and farmland. They are most common in plains, coastal lowlands and hills of suitable habitat. Generally not found at altitude, but has been reported as far up as 2300–3000 m. Humid environments, such as marshes, swamps and rain forests, are avoided.
This species is often found in highly urbanized areas and settlements in the countryside, the attraction being the rodents commensal with man.
As a result, those working outside in these areas are most at risk of being bitten. It should be noted, however, that "D. russelii" does not associate as closely with human habitation as "Naja" and "Bungarus" (cobras and kraits).
Terrestrial and active primarily as a nocturnal forager. However, during cool weather it will alter its behavior and become more active during the day.
Adults are reported to be persistently slow and sluggish unless pushed beyond a certain limit, after which they become fierce and aggressive. Juveniles, on the other hand, are generally more active and will bite with minimal provocation.
When threatened they form a series of S-loops, raise the first third of the body and produce a hiss that is supposedly louder than that of any other snake. When striking from this position, they can exert so much force that even a large individual can lift most of its body off the ground in the process. These are difficult snakes to handle: they are strong and agile and react violently to being picked up. The bite may be a snap, or, they may hang on for many seconds.
Although this genus does not have the heat-sensitive pit organs common to the Crotalinae, it is one of a number of viperines that are apparently able to react to thermal cues, further supporting the notion that they too possess a heat-sensitive organ. The identity of this sensor is not certain, but the nerve endings in the supranasal sac of these snakes resemble those found in other heat-sensitive organs.
It feeds primarily on rodents, especially murid species. However, they will eat just about anything, including rats, mice, shrews, squirrels, land crabs, scorpions and other arthropods. Juveniles are crepuscular, feeding on lizards and foraging actively. As they grow and become adults, they begin to specialize in rodents. Indeed, the presence of rodents is the main reason they are attracted to human habitation.
Juveniles are known to be cannibalistic.
This species is ovoviviparous. Mating generally occurs early in the year, although gravid females may be found at any time. The gestation period is more than six months. Young are produced from May to November, but mostly in June and July. It is a prolific breeder. Litters of 20–40 are common, although there may be fewer offspring and as little as one. The reported maximum is 65 in a single litter. At birth, juveniles are 215–260 mm in length. The minimum length for a gravid female is about 100 cm. It seems that sexual maturity is achieved in 2–3 years. In one case, it took a specimen nearly 4.5 hours to produce 11 young.
These snakes do extremely well in captivity, requiring only a water dish and a hide box. Juveniles feed readily on pinky mice, while the adults will take rats, mice and birds. However, many adults do not feed, with one having refused all food for five months. Breeding is not a problem either. On the other hand, they do make quite dangerous captives. When handled, specimens have been known to use their long, curved fangs to bite right through their lower jaw and into the thumb of the person holding them.
The amount of venom produced by individual specimens is considerable. Reported venom yields for adult specimens range from 130–250 mg to 150–250 mg to 21–268 mg. For 13 juveniles with an average length of 79 cm, the average venom yield was 8–79 mg (mean 45 mg).
The LD in mice, which is used as a general indicator of snake venom toxicity, is as follows: 0.08–0.31 μg/g intravenous, 0.40 μg/kg intraperitoneal, 4.75 mg/kg subcutaneous. For most humans a lethal dose is 40–70 mg. In general, the toxicity depends on a combination of five different venom fractions, each of which is less toxic when tested separately. Venom toxicity also varies within populations and over time.
Envenomation symptoms begin with pain at the site of the bite, immediately followed by swelling of the affected extremity. Bleeding is a common symptom, especially from the gums, and sputum may show signs of blood within 20 minutes post-bite. There is a drop in blood pressure and the heart rate falls. Blistering occurs at the site of the bite, developing along the affected limb in severe cases. Necrosis is usually superficial and limited to the muscles near the bite, but may be severe in extreme cases. Vomiting and facial swelling occurs in about one-third of all cases.
Severe pain may last for 2–4 weeks. Locally, it may persist depending on the level of tissue damage. Often, local swelling peaks within 48–72 hours, involving both the affected limb and the trunk. If swelling up to the trunk occurs within 1–2 hours, massive envenomation is likely. Discoloration may occur throughout the swollen area as red blood cells and plasma leak into muscle tissue. Death from septicaemia, respiratory or cardiac failure may occur 1 to 14 days post-bite or even later.
Because this venom is so effective at inducing thrombosis, it has been incorporated into an in vitro diagnostic test for blood clotting that is widely used in hospital laboratories. This test is often referred to as Dilute Russell's viper venom time (dRVVT). The coagulant in the venom directly activates factor X, which turns prothrombin into thrombin in the presence of factor V and phospholipid. The venom is diluted to give a clotting time of 23 to 27 seconds and the phospholipid is reduced to make the test extremely sensitive to phospholipid. The dRVVT test is more sensitive than the aPTT test for the detection of lupus anticoagulant (an autoimmune disorder), because it is not influenced by deficiencies in clotting factors VIII, IX or XI.
In India, the Haffkine Institute prepares a polyvalent antivenin that is used to treat bites from this species.
Using morphological and mitochondrial DNA data, Thorpe et al. (2007) provided evidence that the eastern subspecies should be considered a separate species, "Daboia siamensis"
A number of other subspecies may be encountered in literature, including:
The correct spelling of the species, "D. russelii" has been, and still is, a matter of debate. Shaw & Nodder (1797), in their account of the species "Coluber russelii", named it after Dr. Patrick Russell, but apparently misspelled his name, using only one "L" instead of two. Russell (1727–1805) was the author of "An Account of Indian Serpents" (1796) and "A Continuation of an Account of Indian Serpents" (1801). McDiarmid et al. (1999) are among those who favor the original misspelled spelling, citing Article 32c (ii) of the International Code of Zoological Nomenclature. Others, such as Zhao and Adler (1993) favor "russellii".
In the future, more species may be added to "Daboia". Obst (1983) reviewed the genus and suggested that it be extended to include "Macrovipera lebetina", "Vipera palaestinae" and "V. xanthina". Groombridge (1980, 1986) united "V. palaestinae" and "Daboia" as a clade based on a number of shared apomorphies, including snout shape and head color pattern. Lenk et al. (2001) found support for this idea based on molecular evidence, suggesting that "Daboia" not only include "V. palaestinae", but also "M. mauritanica" and "M. deserti".
Some herpetologists believe that, because "D. russelii" is so successful as a species and has such a fearful reputation within its natural environment, another snake has even come to mimic its appearance. Superficially, the rough-scaled sand boa, "Gongylophis conicus", has a color pattern that often looks a lot like that of "D. russelii", even though it is completely harmless.