Rinkhals

The rinkhals (/ˈrɪŋk(h)æls/; Hemachatus haemachatus), also known as the ringhals /ˈrɪŋhæls/[4] or ring-necked spitting cobra,[5] is a species of venomous snake in the family Elapidae. The species is found in parts of southern Africa.[1][3] It is not a true cobra in that it does not belong to the genus Naja, but instead belongs to the monotypic 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.[6] The Zimbabwe population was recently described as a new species, H. nyangensis.[7]

Rinkhals
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Elapidae
Genus: Hemachatus
Fleming, 1822
Species:
H. haemachatus
Binomial name
Hemachatus haemachatus
(Bonnaterre, 1790)
  Extant (resident)
  Possibly extinct
  Presence Uncertain & Origin Uncertain
Synonyms

Description
Rinkhals in uKhahlamba-Drakensberg Park.

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.[6] 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:[8]

Distribution
A South African rinkhals with hood spread

This species is found in the Western and Eastern Cape provinces of South Africa, northeast through the Free State, Lesotho, KwaZulu-Natal, South Africa, Western Eswatini, Mpumalanga and parts of Gauteng, South Africa. An isolated population is centred on Inyanga on the Zimbabwe-Mozambique border.[6] There are no recent records from this population; it might be extinct.[1]

Behaviour and diet

The rinkhals has a varied diet. Its main prey is toads,[8] but it also eats small mammals, amphibians, and other reptiles.[10]

Another difference between the rinkhals and the African cobras, is that they are ovoviviparous.[6] They give birth to 20–35 live young, but as many as 65 young have been recorded.[8]

Venom

The venom of the rinkhals is neurotoxic and partially cytotoxic, and is less viscous than that of other African elapids.[6] 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.[10]

A polyvalent antivenom exists in South Africa. A polyvalent antivenom is currently being developed by the Universidad de Costa Rica's Instituto Clodomiro Picado.[11]

Symptoms of a bite
Detail of head

Local symptoms of swelling and bruising is reported in about 25% (a quarter) of cases.[6] General symptoms of drowsiness, nausea, vomiting, violent abdominal pain, cramps and vertigo often occur, as does a mild pyrexial reaction.[6][10]

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.[12]

Habitat

The rinkhals generally prefers grassland habitats because it allows them to blend in with the surroundings. Rinkhals also may live in swamps around southern Africa.[10]

References
  1. Alexander, G.J. (2022). "Hemachatus haemachatus". IUCN Red List of Threatened Species. 2022: e.T177556A197407608. doi:10.2305/IUCN.UK.2022-1.RLTS.T177556A197407608.en. Retrieved 22 August 2022.
  2. Boulenger, G.A. 1896. Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the Colubridæ (Opisthoglyphæ and Proteroglyphæ)... Trustees of the British Museum (Natural History). London. p. 389.
  3. Hemachatus haemachatus at the Reptarium.cz Reptile Database. Accessed 22 August 2022.
  4. "ringhals". The Chambers Dictionary (9th ed.). Chambers. 2003. ISBN 0-550-10105-5.
  5. "Ring Necked Spitting Cobra". Encyclopedia of Life. Retrieved 17 August 2022.
  6. S. Hunter (2000). "Venomous Reptiles".
  7. Major, Tom; et al. (2023). "Museum DNA reveals a new, potentially extinct species of rinkhals (Serpentes: Elapidae: Hemachatus) from the Eastern Highlands of Zimbabwe". PLOS One. 18: e0291432. doi:10.1371/journal.pone.0291432.
  8. R. Mastenbroek (2002). "Rinkhals". Archived from the original on 2007-11-24.
  9. Branch, Bill. 2004. Field Guide to Snakes and Other Reptiles of Southern Africa, Third Revised edition, Second impression. Ralph Curtis Books. Sanibel Island, Florida. 400 pp. ISBN 0-88359-042-5.
  10. B. Branch (1988). Field Guide to the Snakes and Other Reptiles of southern Africa. Struik, Cape Town.
  11. Sánchez, Andrés; et al. (2017). "Expanding the neutralization scope of the EchiTAb-plus-ICP antivenom to include venoms of elapids from Southern Africa". Toxicon. 125: 59–64. doi:10.1016/j.toxicon.2016.11.259. PMID 27890775. S2CID 24231215.
  12. BBC Earth Unplugged (2018-03-10), Rinkhals Snake Plays Dead | Deadly 60 | Earth Unplugged, retrieved 2019-02-16

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Further reading
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