The rinkhals (; ''Hemachatus haemachatus''), also known as the ringhals or ring-necked spitting cobra, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

venomous snake Venomous snakes are species of the suborder Serpentes that are capable of producing venom, which they use for killing prey, for defense, and to assist with digestion of their prey. The venom is typically delivered by injection using hollow or g ...

in the family

Elapidae Elapidae (, commonly known as elapids ; grc, ἔλλοψ ''éllops'' "sea-fish") is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus Emydoce ...

. The species is found in parts of southern Africa. It is not a true cobra in that it does not belong to the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Naja ''Naja'' is a genus of venomous elapid snakes commonly known as cobras (or "true cobras"). Members of the genus ''Naja'' are the most widespread and the most widely recognized as "true" cobras. Various species occur in regions throughout Afric ...

'', but instead belongs to the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

genus ''Hemachatus''. While rinkhals bear a great resemblance to true cobras they also possess some remarkable differences from these, resulting in their placement outside the genus ''Naja''.

Description

Colouration varies throughout its distribution area, but a characteristic of the species is the belly is dark with one or two light-coloured crossbands on the throat. Their average length is 90–110 cm. Some individuals may have a mostly black body, while others are striped. Rinkhals scales are distinct from those of ''Naja'' cobras in that they are ridged and keel-like.

Scale pattern

Scalation In most biological nomenclature, a scale ( grc, λεπίς, lepís; la, squāma) is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran (butterfly and moth) species, scales are plates on the surf ...

: *dorsal scales are keeled *17–19 rows of

dorsal scales In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales. Campbell JA, Lamar WW (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publ ...

at midbody *116–150

ventral scales In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that cont ...

*anal plate is entire *30–47 subcaudal scales, paired *7 upper

labial scales The labial scales are the scales of snakes and other scaled reptiles that border the mouth opening. These do not include the median scales on the upper and lower jawsWright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates (7 ...

*upper labials 3 and 4 entering the eye *1 pre

ocular Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

(rarely up to 3) *3 postoculars *8–9 lower labials

Distribution

This species is found in the Western and Eastern Cape provinces of

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...

, northeast through the Free State,

Lesotho Lesotho ( ), officially the Kingdom of Lesotho, is a country landlocked as an enclave in South Africa. It is situated in the Maloti Mountains and contains the highest mountains in Southern Africa. It has an area of over and has a population ...

Transkei Transkei (, meaning ''the area beyond he riverKei''), officially the Republic of Transkei ( xh, iRiphabliki yeTranskei), was an unrecognised state in the southeastern region of South Africa from 1976 to 1994. It was, along with Ciskei, a Ba ...

KwaZulu-Natal KwaZulu-Natal (, also referred to as KZN and known as "the garden province") is a province of South Africa that was created in 1994 when the Zulu bantustan of KwaZulu ("Place of the Zulu" in Zulu) and Natal Province were merged. It is loca ...

, South Africa, Western

Eswatini Eswatini ( ; ss, eSwatini ), officially the Kingdom of Eswatini and formerly named Swaziland ( ; officially renamed in 2018), is a landlocked country in Southern Africa. It is bordered by Mozambique to its northeast and South Africa to its no ...

Mpumalanga Mpumalanga () is a province of South Africa. The name means "East", or literally "The Place Where the Sun Rises" in the Swazi, Xhosa, Ndebele and Zulu languages. Mpumalanga lies in eastern South Africa, bordering Eswatini and Mozambique. ...

and parts of

Gauteng Gauteng ( ) is one of the nine provinces of South Africa. The name in Sotho-Tswana languages means 'place of gold'. Situated on the Highveld, Gauteng is the smallest province by land area in South Africa. Although Gauteng accounts for only ...

, South Africa. An isolated population is centered on Inyanga on the

Zimbabwe Zimbabwe (), officially the Republic of Zimbabwe, is a landlocked country located in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Botswana to the south-west, Zambia to the north, and ...

Mozambique Mozambique (), officially the Republic of Mozambique ( pt, Moçambique or , ; ny, Mozambiki; sw, Msumbiji; ts, Muzambhiki), is a country located in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi ...

border. There are no recent records from this population; it might be extinct.

Behaviour and diet

The rinkhals has a varied diet. Its main prey is

toads Toad is a common name for certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and large bumps covering the parotoid glands. A distinction between frogs and toads is not made in scienti ...

, but it also eats small

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...

amphibian Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...

s, and other

reptiles Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates ( lizards and snakes) and rhynchoceph ...

. Another difference between the rinkhals and the African cobras, is that they are ovoviviparous. They give birth to 20–35 live young, but as many as 65 young have been recorded.

Venom

The

venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a st ...

of the rinkhals is

neurotoxic Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specificall ...

and partially

cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating c ...

, and is less

viscous The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the in ...

than that of other African

elapids Elapidae (, commonly known as elapids ; grc, ἔλλοψ ''éllops'' "sea-fish") is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus Emydocep ...

. When confronting a human, it generally aims its venom at the face. If the venom gets injected, it causes great amount of pain and even necrosis due to the cytotoxic effect. If the venom enters the eyes, it causes great pain. A polyvalent antivenom exists in South Africa. A polyvalent antivenom is currently being developed by the

Universidad de Costa Rica The University of Costa Rica (Spanish: ''Universidad de Costa Rica,'' abbreviated UCR) is a public university in the Republic of Costa Rica, in Central America. Its main campus, Ciudad Universitaria Rodrigo Facio, is located in San Pedro Mo ...

Instituto Clodomiro Picado The Instituto Clodomiro Picado is a research center in Vázquez de Coronado, San José Province, Costa Rica. Established in 1970, the institute is a research unit of the Universidad de Costa Rica, responsible for the production of snake antiophi ...

Symptoms of a bite

Local symptoms of swelling and bruising is reported in about 25% (a quarter) of cases. General symptoms of drowsiness,

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of th ...

, vomiting, violent abdominal pain, cramps and

vertigo Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...

often occur, as does a mild

pyrexia Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using va ...

l reaction.

Defensive behaviour

If distressed, the rinkhals spreads its hood, showing its distinctive, striped neck. It can spray its venom up to 2.5 m. It generally rears up and flings its body forward as it sprays its venom because unlike true spitting cobras, its aim is very poor but it can spit without doing this. It is also known to fake death (thanatosis) very convincingly by rolling onto its back with its mouth agape.

Habitat

The rinkhals generally prefers

grassland A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...

habitats because it allows them to blend in with the surroundings. Rinkhals also may live in

swamps A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

around

southern Africa Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number o ...