Philippine cobra

Philippine cobra
Conservation status
Near Threatened (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Family:	Elapidae
Genus:	Naja
Species:	N. philippinensis
Binomial name
Naja philippinensis Taylor, 1922
Distribution of the Philippine cobra

The Philippine cobra (Naja philippinensis) also called Northern Philippine cobra, is a stocky, highly venomous spitting cobra native to the northern regions of the Philippines. The Philippine cobra is called "ulupong" in Tagalog and "Agwason" in Cebuano-Bisaya.

Etymology

Naja philippinensis was first described by American herpetologist Edward Harrison Taylor in 1922. The generic name naja is a Latinisation of the Sanskrit word nāgá (नाग) meaning "cobra". The specific epithet philippinensis is Latin and literally means "from the Philippine Islands".

Description

The Philippine cobra is a stocky snake of medium length that has long cervical ribs capable of expanding, so that when threatened a hood can be formed. The average length of this species is 1.0 metre (3.3 ft). The species can grow to lengths of 1.6 metres (5.2 ft) However, sub-populations of the species, particularly specimens from Mindoro Island, are said to attain lengths of 2 metres (6.6 ft), but these are unverified and unconfirmed claims. If true, however, 2 metres (6.6 ft) would be very rare and would be considered the absolute maximum for this species. The head is elliptical, depressed, slightly distinct from neck with a short, rounded snout and large nostrils. The eyes are moderate in size with dark brown and round pupils, typical of other cobra species and similar to other elapids in general. It has a fairly stocky build for an elapid and adult snakes are uniformly light to medium brown, while the juveniles tend to be a darker brown in color. They have 23-27 scale rows around the neck and 21 just above the middle part of the body; 182-193 ventrals, 36-49 subcaudals, and basal pairs are sometimes undivided.

Distribution

The Philippine cobra occurs mostly in the northern regions of the Philippines. They can be found on the islands of Luzon, Mindoro, Catanduanes, and Masbate. It is also likely that this species may occur in other neighboring islands, but this remains unconfirmed. Records from the Calamianes group and Palawan require confirmation.

Habitat

Philippine cobra’s habitat include low-lying plains and forested regions, along with open fields, grasslands, dense jungle, agricultural fields, and human settlements. This species of cobra is particularly fond of water and it can always be found very close to ponds, rivers, or large puddles of water.

Diet

This species feeds predominantly on small mammals, frogs, and even other snakes. Small rodents such as mice and small rats are their preferred prey and makeup the majority of their diet. However, they will also eat other snakes, including juvenile King cobra's, small lizards, frogs, eggs, and when the opportunity arises, small birds are also taken.

Predators

Predators of this species of cobra include humans, birds of prey, the King cobra, and the mongoose. Large rats that have been bitten by this snake and are in a position to fight back, often do so. Although rare, large rats have been known to fatally wound the snake by scratching, biting, or even poking one or both of the snakes eyes out. Of course, the rat ends up succumbing to the venom, but the snake will often sustain injury to one or both eyes, potentially becoming blind, and severe bites to the snout region leave the snake vulnerable to all sorts of infections and diseases.

Venom

The venom of the Philippine cobra is a potent postsynaptic neurotoxin which affects respiratory function and can cause neurotoxicity and respiratory paralysis, as the neurotoxins interrupt the transmission of nerve signals by binding to the neuro-muscular junctions near the muscles. Research done on the venom of this species has shown that its venom is purely a neurotoxin, with no apparent necrotizing components and no cardiotoxins. They are capable of accurately spitting their venom at a target that is up to 3 metres (9.8 ft) away from where they are. The symptoms of a bite might include headache, nausea, vomiting, abdominal pain, diarrhea, dizziness, and difficulty breathing. Bites by the Philippine cobra produce prominent neurotoxicity with minimal to no local signs. A study of 39 patients envenomed by the Philippine cobra (Naja philippinensis) was conducted in 1988. Neurotoxicity occurred in 38 cases and was the predominant clinical feature. Respiratory paralysis developed in 19 patients, and was often rapid in onset-in 3 cases apnea occurred within 30 minutes of the bite. There were 2 deaths, both in patients who were moribund upon arrival at the hospital. Three patients developed necrosis, and 14 individuals with systemic symptoms had no local swelling at all. Both cardiotoxicity and reliable nonspecific signs of envenoming were absent. Bites by the Philippine cobra produce a distinctive clinical picture characterized by severe neurotoxicity of rapid onset and minimal local tissue damage.

Although venom toxicity values can vary greatly even among specimens of the same species, the Philippine cobra has the most toxic venom among all of the Naja (cobra) species according to all known toxicological studies which give the species a value, thus making it the most venomous cobra species in the world. The subcutaneous LD₅₀ for this species is 0.20 mg/kg and the average venom yield per bite is 90–100 mg (with a maximum yield of 250 mg). In comparison, the corresponding SC LD₅₀ for Naja naja (Indian cobra) venom is 0.45 mg/kg according to Dr. Bryan Grieg Fry. SC LD₅₀ values for other cobra's include 1.15 mg/kg for Naja haje (Egyptian cobra), 2 mg/kg for Naja nigricollis (Black-necked spitting cobra), 0.72 mg/kg for Naja nivea (Cape cobra), and 0.53 mg/kg for Naja atra (Chinese cobra).

External links

• U.S. Naval Medical Research
• Naja philippinensis
• "Naja philippinensis - Mario Lutz`s HerpaWorld Institute"
• "Wolfgang Wüster's - Asiatic Cobra Page"
• LUTZ, M . (2006) Die Kobras des philippinischen Archipels - Teil I: Die Philippinen-Kobra, Naja philippinensis TAYLOR, 1922, SAURIA, Berlin, 28 (3): 31-37