Common Krait

common krait
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Elapidae
Genus:	Bungarus
Species:	B. caeruleus
Binomial name
Bungarus caeruleus (Schneider, 1801)
Synonyms
Pseudoboa caerulea Schneider, 1801 Bungarus candidus Var. CÆRULEUS Boulenger, 1896

The common krait (Bungarus caeruleus, also known as Indian krait or Blue krait) is a species of genus Bungarus found in the jungles of the Indian subcontinent.^[1] It is a member of the "big four", species inflicting the most snakebites in India.

Description

The body colour varies from a dark steely blue-black to a pale faded bluish grey. The average length is 0.9 meters (2 ft 11 in) but they can grow to 1.75 meters (5 ft 9 in).^[1] Subcaudal scales after the anal plate are not divided. It has large hexagonal scales running down its spine. The narrow white cross bands are more prominent near the tail region.

The male is larger than the female and also has a longer tail.

Common names

• Hindi - Karait.
• Bengali - Kalach, Domnachiti (North Bengal), Shiyar Chanda (South Bengal).
• Kannada - Kattige haavu.
• Telugu - Katla paamu.
• Gujarati - Kala taro.
• Marathi - Manyar, kanadar.
• Oriya - Chitti.
• Tamil - Kattu viriyan, Yennai viriyan, Yettadi viriyan.
• Malayalam - Velli Kattan (Malabar and Cochin), Ettadi veeran (Travancore).
• Sinhala - Karawala.
• Tulu - Katta Kadambale.

Geographic range

Peninsular India from Sindh (Pakistan), to the West Bengal plains. It occurs throughout South India and Sri Lanka at elevations up to about 1600 metres.^[1]

Habitat

Inhabits a wide variety of habitat in its range. It is found in fields, low scrub jungle as well as inhabited areas. They are known to take up residence in termite mounds, brick piles, rat holes and also inside houses.^[1] It is fond of water and is frequently found in it or within proximity to a water source.

Feeding

These snakes prey on other snakes, lizards, frogs, rats, and mice. They will devour their young being cannibalistic in nature. Young are known to eat arthropods. As per Daniels, the common krait feeds primarily on other snakes, including "blind worms" (snakes of the genus Typhlops) and other kraits, and also feeds on frogs and lizards and small mammals. This snake is nocturnal. It is very active and agile at night. It often hides in rodent holes, loose soil or beneath debris, so it is rarely seen during day.

Behavior

Behavioral differences during day and nighttime have been reported in Bungarus caeruleus. During the day it is sluggish and rolls its body into a loose coiled ball, keeping its head well-concealed. In balled condition, the snake allows considerable handling, however, over handling often instigates bites. At night the snake is very active, escapes by hissing loudly, or keeping still, occasionally biting the source of the annoyance.

When agitated, it will coil up with head concealed, body flattened, and make jerky movements. May also lift its tail. Reluctant to bite, but when it does bite, it typically bites and holds on for awhile, which enables it to inject considerable amounts of venom. Generally docile and unaggressive during the day, it may become aggressive at night if threatened.

Venom

The Indian krait's venom consists mostly of powerful neurotoxins which induce muscle paralysis. Clinically, its venom contains pre-synaptic and post-synaptic neurotoxins.^[1] These neurotoxins generally affect the nerve endings near the synaptic cleft of the brain.

In mice, the LD₅₀ values of its venom are 0.365 mg/kg SC, 0.169 mg/kg IV and 0.089 mg/kg IP.^[2][3] while the average venom yield is 8—20 mg.^[2]

Kraits are nocturnal and seldom encounter humans during daylight hours, so incidents are rare. There is frequently little or no pain from a krait bite and this can provide false reassurance to the victim. Typically, victims complain of severe abdominal cramps, accompanied by progressive paralysis. Once bitten, the absorption of the venom into the victim can be considerably delayed by applying a pressure bandage to the bite site (using about the same tension as one uses for a sprained ankle) and immobilising the area. This allow for gentle transport to medical facilities, where the venom can be treated when the bandage is removed. As there are no local symptoms, a patient should be carefully observed for signs of paralysis (e.g., the onset of ptosis) and treated urgently with antivenom. It is also possible to support bite victims via mechanical ventilation, using equipment of the type generally available at hospitals. Such support should be provided until the venom is metabolised and the victim can breathe unaided. If death occurs it takes place approximately 6–8 hours after the krait bite. Cause of death is general respiratory failure, i.e. suffocation.^[4]

Often in rainy season the snakes come out of their hiding places and find refuge on dry places inside a house. If bitten by it in sleep the victim seldom comes to know as the bite feels more like an ant bite or a mosquito bite. The victim may be dead before he even wakes up.

One such case was recently reported in Indore, where Mr Rajan Jadhav, an various accent instructor of English language was bitten by it inside his house, and was declared dead on arrival at the hospital.

Prof Krishna Shrivastava has made this as reference that Mr. Mohsin Khan, student SSBT's College of Engineering Jalgaon, bitten by Krait on 24/8/11 in morning at 4 AM, after giving 79 Anti Venom,survived.

A clinical toxicology study gives an untreated mortality rate of 70–80%.^[1]

Footnotes

1. ^ ^{a b c d e f} "Clinical Toxinology-Bungarus caeruleus". http://toxinology.com/fusebox.cfm?fuseaction=main.snakes.display&id=SN0015. 
2. ^ ^{a b} "LD50". http://www.seanthomas.net/oldsite/ld50tot.html. 
3. ^ "LD50 menu". http://www.kingsnake.com/toxinology/LD50/LD50men.html. 
4. ^ [http://drdavidson.ucsd.edu/Portals/0/snake/Bungarus.htm "Medical Management for bites by Kraits (Bungarus species)"]. http://drdavidson.ucsd.edu/Portals/0/snake/Bungarus.htm. 

Other reference

Romulus Whitaker (1978). COMMON INDIAN SNAKES: A Field Guide. Macmillan India Limited. 

Other culture

In the famous story in The Jungle Book, "Rikki Tikki Tavi," Karait, a dustbrown krait, threatens the boy. Rikki, a young mongoose does battle with the snake and the narrator emphasizes that he is a dangerous opponent, even more than a cobra in some respects. Regardless of the risk and the mongoose's inexperience, Rikki defeats him.

In the 9th novel of the Women's Murder Club, "8th Confession" by James Patterson, the killer used a krait snake to poison and kill her victims.

• http://wildlifesos.org/rescue/reptiles/big-4 - a site about venomous snakes in India.
• Snakes in Sri Lanka