Black-necked spitting cobra: Difference between revisions

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 mostly in sub Saharan Africa. Like other venomous snakes, it is feared throughout its range. This species has the capability of spitting or 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.

Naja nigricollis was first described by Norweigan zoologist Johan Reinhardt in 1843. The generic name naja is a Latinisation of the Sanskrit word nāgá (नाग) meaning "cobra". The specific epithet nigricollis is Latin for "black-necked": niger meaning "black" and collis meaning "neck".^[2]

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 will 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 the reddish colour on the belly. Some other specimens are deep reddish brown and yet others can be an olive brown.^[3] Some can even be striped black and white.^[4] There are 21-23 dorsal scales at the mid-body, 182-196 ventral scales, and 54-66 subcaudal scales.^[5] 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 these subspecies are smaller than N. n. nigricollis, both subspecies average adult lengths of less than 1.5 metres (4.9 ft).^[3][4]

The species is very common and is widespread throughout Sub Saharan Africa and is 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 found in Nigeria, Liberia, Senegal, and Benin in western Africa. It is 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.^[3]

Naja n. nigricollis usually inhabits savanna and semi-desert regions of Africa. However, they can be found in high altitudes up to 1,800 metres (5,900 ft) as well as in tropical and sub-tropical regions of central Africa in moist savanna and cleared former forest regions, particularly near rivers and streams.^[6] Adaptable snakes, Naja n. nigricollis occurs in south eastern Nigeria where, their habitat has been transformed from rainforest to man-made farmlands, plantations, suburban areas, and a few fragmented forests. This species of cobra has found advantages in the drastic changes which have taken place in Nigeria's rainforests. A study by herpetoligist Luca Luiselli, suggests this snake now forages in much drier microhabitats.^[7]

The range of the nominate subspecies, Naja n. nigricollis is currently expanding from the south eastern regions of Nigeria to the more desert and arid like conditions in the central part of the nation of Nigeria.^[5] They also live in coastal scrubs and dry grasslands. Like other cobra species, they may find abandoned termite mounds or rodent holes to hide or cool off. However, tree trunks seem to be their favourite of hiding places. They are excellent tree climbers and thus can be arboreal at times. Because they are so common across Africa, they are encountered in villages or small towns where they may come in direct contact with people.^[5]

The other two subspecies are found only in the desert regions of southern Africa.^[8]

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 will eat lizards, eggs and other snakes.^[8]

Like other snakes, it may fall prey to different raptors, especially different species of snake eagles which migrate to Africa when it is winter in the Northern hemisphere. The Short-toed Snake Eagle (Circaetus gallicus) may be a particular threat as it is almost strictly an ophiophagus raptor.^[9]

Like other spitting cobras, this species 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.^[8][6]

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. ^[3]

Like other cobra species, this snake is oviparous.^[10] The mating season of this species can vary from the end of winter (September) to the beginning of summer (December). Usually the mating season is the same whether in captivity or in the wild. Females generally lay between 8-20 eggs at a time. The gestation period lasts about 90-100 days, but once the eggs are laid it takes about 60-70 days for the babies to hatch, and they need to be in a temperature of 28-30 °C (82.4-86 ºF). At birth the babies are about 20 to 25 centimeters (7.9 to 9.8 in) in length and are completely independent from birth.

The venom of Naja nigricollis is somewhat unique among elapids in that it consists primarily of hemotoxins,^[11] but with other components also. It retains the typical elapid neurotoxic properties while combining these with hemotoxins,^[11] highly potent cytotoxins (necrotic agents),^[12] and cardiotoxins.^[13] 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%),^[14] when death occurs it is usually due to asphyxiation by 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 200 to 350 mg ( dry weight ) according to Minton (1974).^[6][15]

• Red Spitting Cobra
• Mozambique Spitting Cobra