Naja nigricollis


Naja nigricollis
Black Necked Spitting Cobra
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Elapidae
Genus: Naja
Species: N. nigricollis
Binomial name
Naja nigricollis
Common names: Spitting Cobra, Black Necked Spitting Cobra, Western Barred Spitting Cobra, Zebra Spitting Cobra (subspecies nigricincta), Black Spitting Cobra (subspecies woodi)

Naja nigricollis is a species of spitting cobra found in Sub Saharan Africa. It is feared throughout its range and has the capability of spraying venom at attackers as a defensive mechanism. There are three subspecies, including the nominate subspecies, which is the most common and widespread of the three.

Contents

Description

Naja nigricollis is a moderately sized venomous snake with a moderately distinct head; the shape of the head is due primarily to the two large venom glands found on each side of the head. Their colour can vary depending on region of origin. Some specimens are black or pale grey with a yellow or reddish ventral side with a broad black neck band. They'll often have an orange or pinkish bar on the neck. Other specimens can be yellowish brown or have a yellow copper colour and are missing the bandings around the neck and also the reddish colour on the belly. Some other specimens are deep reddish brown and yet others can be an olive brown.[1] Some can even be striped black and white.[2] There are 21-23 dorsal scales at the mid-body, 182-196 ventral scales, and 54-66 subcaudal scales.[3] This species generally grows to a length of 1.2 metres (3.9 ft) to 2.2 metres (7.2 ft), but some specimens have been known to attain lengths up to 2.8 metres (9.2 ft). These sizes are subject to trends based on geographic location and subspecies. The subspecies N. n. nigricincta, also known as the Zebra Spitting Cobra, is given its name due to the dark crossbars that run the length of the snakes body. The subspecies N. n. woodi is solid black and is found only in the desert areas of Southern Africa. Both of the non-nominate subspecies are smaller than N. n. nigricollis, both subspecies average adult lengths of less than 1.5 metres (4.9 ft).[4][5]

Geographic Range

The species is very common and is widespread throughout Sub Saharan Africa. It can be found in western, eastern, central, and southern Africa. Naja n. nigricollis is the most common and widespread subspecies. It can be found all along eastern Africa south of the Sahara desert in Kenya, Uganda, Tanzania, Rwanda, and southern Somalia. It is also found in Nigeria, Liberia, Senegal, and Benin in western Africa. It's common in Zambia, Central African Republic, Angola, and Cameroon in central Africa. In southern Africa, it is found in South Africa, Swaziland, Botswana, Namibia, Mozambique, and other nations. Naja n. woodi is found only in the desert regions of Namibia and South Africa. Naja n. nigricincta is found in central and northern Namibia and southern Angola.[6]

Habitat

Naja n. nigricollis usually inhabit savanna and semi-desert regions of Africa. However, they can be found in high altitudes up to 1,800 metres (5,900 ft) and can even be found in tropical and sub-tropical regions of central Africa. They are highly adaptable and hardy snakes. Naja n. nigricollis are found in south eastern Nigeria where its habitat has been altered from a tropical rainforest to man-made farmlands, plantations, suburban areas, and a few fragmented forests (Luiselli, 2001). According to Luiselli’s studies (2001), this spitting cobra has taken an advantage to the deforestation of Nigeria. It is suggested from the study that the species forages in much drier microhabitats. Naja n. nigricollis has been currently extending its range from the south eastern regions of Nigeria to the arid savannas of central Nigeria (Luiselli, 2001).[7] They also live in coastal scrubs and dry grasslands. They can be found hiding in termite mounds and rodent holes, although tree trunks are their favorite hiding places. They are excellent tree climbers and can sometimes be found in trees. They are also commonly found in cities and villages, where they come in direct contact with people.[7][3]

The other two subspecies are found only in the desert regions of southern Africa.

Venom

The venom of Naja nigricollis is characteristic of the African spitting cobras. It retains the typical elapid neurotoxic properties while combining these with cytotoxins. This snake is potentially lethal and has been responsible for numerous human fatalities. Bite symptoms include severe external hemorrhaging and tissue necrosis around the bite area and difficulty breathing. Although mortality rate in untreated cases is low (~ 5-10%),[8] death generally occurs due to asphyxiation due to paralysis of the diaphragm. The LD50 of Naja nigricollis is 2 mg/kg SC and 1.15 mg/kg IV. The average venom yield per bite of this species is 150-350 mg.[9][10]

Behavior

Unlike other snakes, Naja nigricollis can be either nocturnal or diurnal depending on the time of year, geographic location, and average daytime temperature. This adaptability allows the snake to better regulate its body temperature and to gain access to the most abundant food sources of a particular area. Naja nigricollis feeds primarily on small rodents such as small rats and mice, but they'll also eat lizards, eggs, and other snakes.

It is preyed upon by numerous species of predatory bird, such as the secretary bird. Naja nigricollis is also an occasional target of different species of Mongoose, which uses its speed, reflexes and partial immunity to the snake's venom to attack and kill the snake.

This snake, like other spitting cobras, is known for its ability to project venom at a potential threat. The venom is an irritant to the skin and eyes. If venom enters the eyes, symptoms include extreme burning pain, loss of coordination, partial loss of vision and permanent blindness. Naja nigricollis is known for its tendency to liberally spit venom with only the slightest provocation. However, this aggressiveness is counterbalanced by the fact that Naja nigricollis is less prone to bite than other related species.

This species is sometimes found in captivity, and wild caught individuals are generally nervous and prone to spitting. Captive bred animals tend to be much more docile and calm when compared to their wild caught counterparts. The keeping of this species should never be attempted by anyone without the proper education and experience.

Taxonomy

Subspecies Common name Geographic range Regional Differences
N. n. nigricollis Black Necked Spitting Cobra Eastern Africa in Tanzania, Kenya, Uganda, Burundi, southern Somalia, and Rwanda. Western Africa in Nigeria, Liberia, Benin, Sierra Leone, and Senegal. Southern Africa in South Africa, Namibia, Botswana, and Mozambique. Central Africa in Zambia, Central African Republic, Angola, and Cameroon. The nominate subspecies.
N. n. nigricincta Zebra Spitting Cobra Central and Northern Namibia and Southern Angola. Grey brown, yellow, or pink with dark bands from head to tail.
N. n. woodi Black Spitting Cobra Central and Western Namibia, South Africa (Cape Province). Solid black, or grey body with black hood and head. In some cases it is outwardly identical to N. n. nigricollis and can only be distinguished by size and range.

See also

References


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