Tuesday, June 17, 2014

Spectacled Cobra : The Reputed Hiss (නයා / නාගයා)

Even though there are more than 3000 species of snakes in the world, There is one snake species that get's reputation and worships from humans than any other snakes. Like the post title suggests, when you hear that hissing, you certainly know what are you dealing with. It's the snake that symbolize the word "Serpent" sometimes. Fearsome reputation, mythical and religious believes, respected in animal kingdom , The Spectacled cobra also known as the Indian cobra is the most well known Cobra species in the genus Naja. Here in Sri Lanka you face this snake in almost all parts of the country.

                                                  (Image Credit- mM,Flickr)

True Cobras are belonging to the genus Naja which includes number of 20-22 species. The reason i used the term "True Cobras" is people think some non Naja snake species like King Cobra (Ophiophagus hannah) and Rinkhals (Hemachatus haemachatus) are true cobra's just because they show some iconic cobra characteristics like spreading hood and spitting venom. Spectacled cobra classified as Naja naja with no recognized sub species in the genus Naja of the sub Family Elapinae. In our native language sinhala, we call this snake as "නයා" (Naya) or "නාගයා"(Nagaya). If you searched more you will understand that the name Naya/Nagaya we used to call comes from the ancient cultures of India and the Sanskrit word "Naga". Spectacled cobra holds the record of the largest venomous snake species in Sri Lanka.

Spectacled cobra was first described back in 1758 by the Swedish herpetologist and physician Carl Linnaeus. This particular snake takes a big roll in Hindu mythology, culture and religion as well as in Sri Lankan history and mythology. Kaliya the 110 headed cobra ruled the Yamuna river in Hindu mythology was a venomous Naga defeated by Krishna, the eighth incarnation of the Hindu god Vishnu. The statues of Hindu god Shiva has a cobra coiled around his neck symbolizing the world illusion. These cultural mythical believes can be still seen today in India and Nag panchami festival where Cobras are worshiped, bathed and fed with milk is a good example for that. The ancient reports from Sri lanka shows Naga Tribed lived before 250BC, they worshiped cobras and lost their tribe after the spread of Buddhism.

                                                        (image credit- Dr.Anand & Geeta Pereira)

Naja naja is distributed in India, Sri Lanka, Nepal, Pakistan, Bhutan and Bangladesh. in Sri Lanka it can be seen widely distributed in plains and mid hill areas except Montane region. Cobras are easy to identified due to their native threat pose so as Spectacled cobra. There are two black dots on its dorsal aspect. These two black dots are usually connected outside with a black arc resembling a spectacle or the letter “ප“ (Pa) in sinhala alphabet. This spectacled mark varies from snake to snake. It's a key factor to identify the snake. This mark on dorsal aspect is visible even the snake is not in a hooded posture. reaching lengths from 20cm (Hatchlings) to 240cm/8 Feet (Fully grown adult, but average length of a adult is between 6-7 feet) spectacled cobra is the largest venomous snake in Sri Lanka. The dorsal color can be varies from blackish brown to grey. Albino specimens and cream rose color specimens are also reported in the island. apart from Albinos and Leucistic morphs, White strips can be seen on the dorsal body.Sometimes these strips are in a zigzag formation making easy to identify the snake. Leucistic Spectacled cobras are also reported in the wilds of India.

Basically a diurnal terrestrial snake. but often found in mid tree branches as well. Nocturnal behavior is also reported. likes to take refuge in termite mounds and underground rodent holes. Except high montane region, this snake is widely distributed in midhills and plains, naja naja has a distinct head from body, 23 to 25 mid body scales, 176-200 ventral scales,  53-67 sub caudal scales can be seen. talking about the scales, dorsal scales are oval and smooth. dorsal scales on sides are larger than scales on vertrabal area. one cuneater scale can be seen on both sides of the head. an adult cobra shed it's skin average six times a year

Diet of spectacled cobra varies from small mammals including rodents to amphibians like toads and frogs. ophiophagy feeding behavior can be seen, young russell's vipers are often became a prey for cobras. lizards,birds and eggs are also include in the diet.

Following video shows a spectacled cobra feeding on a Russell's viper

Spectacled cobra is a highly venomous snake, it is primarily equipped with powerful post synaptic neurotoxic venom. This snake can inject venom from 170mg up to 250mg in a single bite where 16mg is the lethal doze for a human. The venom attacks the central nervous system, shutting down the synaptic gaps between nerves which leads to muscle paralysis and cardiotoxic compounds leads to cardiac arrest. respiratory failure can be also expected. Envenomation symptoms can be seen between 15mins to 2 hours after the bite. mortality rate of a untreated bite is 15-20% , using venom is a last resort for a cobra when it comes defense. cobras often give dry bites when defending it self. it is a shy snake but can be aggressive when provoked. proteroglyph short fixed fangs are present like in all Elapids. Many cobra bite cases led to extensive tissue necrosis ,so this is not a snake to get bitten by.

                                                                 fangs of naja naja

Symptoms of Envenomation 

Symptoms can be followed with few stages, Neuromuscular and neurological symptoms are the first signs of envenomation of a cobra bite.

*Eye lids dropping
*Muscle paralysis
*Respiratory paralysis

General Symptoms- *Vomiting
                               *Pain around bite site
                               *Lower abdominal pain

Cardiotoxity Symptoms- *High blood pressure

Other Symptoms - * Tissue Necrosis

This cobra species lays 5 to 25 eggs between April and July. hatchlings emerges after 50 to 90 days later. Female cobra guard her nesting area until eggs are ready to hatch and relatively more aggressive. hatchlings are already equipped with venom glands and they have potent venom as adults. hatchlings and young cobras are always be on alert and tend to bite if provoked. This video clip in the link-Click Here to see the video shows mating , laying eggs and hatching of eggs.

                                                                (Image Credit- Monyet)

Snake charmers are common sight in the island, they use spectacled cobras to find their daily income. these people use a special flute to make a music to tame the cobra. but since snakes doesn't have external ears, they cant hear it. it follows the movements of the flute resulting a snake dance. many people think this is how cobras react to music. but it's wrong. sometimes snake charming is a torture to the animal. snake charmers remove the venom glands of cobras and release them to the wild after years of use. these animals often die from infections and some survive thanks to the instincts. studies found that, cobras with no venom glands which released by snake charmers often rely on small prey they can bite and hold on. knowing the lack of venom naturally adopts the animal to this kind of feeding behavior.

Myths about Cobra among Sri Lankan people.

* Cobra is a vengeful animal, if a cobra bites the ground ,that means it's cursing the person who disturbed it and will bite and kill that person someday - Cobra's are not vengeful animals,

*If you killed someone, that person will reborn as a cobra and takes revenge. - This is another myth,

*Cobra mate with Ratsnakes, the offspring is trinket snake- Snakes doesn't mate with other species except their own kind. besides that cobras love to have a rat snake for it's meal.

*Cobras keep a special gem called "Naga Manikya (Cobra gem)" it vomits the gem at night to use it's light for search of prey. - Snake anatomy never support such objects inside them, another funny myth.

Apart from these, some Indian people believes cobra species likes to drink milk which is a myth but in Nag panchami day they offer milk to cobras..this is bad for the snakes health, reptile stomach isn't build to digest milk, consuming milk is a mammal thing. Snake charmers keep the animals without giving water for few days before Nagpanchami so the animal will drink any available liquid to keep the moisture in it's mouth.

Protecting these magnificent animals helps us to reduce the pests in agriculture, Snake venom is used to make varies medicines. Therefore we humans must appreciate the contribution of these snakes in our ecosystem and we must protect them at any cost.

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