Rinkhals

The rinkhals (Hemachatus haemachatus), also called the ringhals or ring-necked spitting cobra, is a species of venomous elapid found in parts of southern Africa. 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.[3]

Rinkhals

Least Concern  (IUCN 3.1)
Scientific classification
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)
Synonyms
  • Coluber haemachates
    Bonnaterre, 1790
  • Vipera haemachates
    - Latreille, 1802
  • Sepedon haemachates
    - Merrem, 1820
  • Naja haemachates
    - Schlegel, 1837
  • Aspidelaps haemachates
    - Jan, 1863
  • Sepedon hæmachates
    - Boulenger, 1896
  • Hemachatus haemachatus
    - Stejneger, 1936[1][2]

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.[3] 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:[4]

  • dorsal scales are keeled[5]
  • 17–19 rows of dorsal scales at midbody
  • 116–150 ventral scales
  • anal plate is entire
  • 30–47 subcaudal scales, paired
  • 7 upper labial scales
  • upper labials 3 and 4 entering the eye
  • 1 preocular (rarely up to 3)
  • 3 postoculars
  • 8–9 lower labials

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, Transkei, KwaZulu-Natal, South Africa, Western Swaziland, Mpumalanga and parts of Gauteng, South Africa. An isolated population is centered on Inyanga on the Zimbabwe-Mozambique border.[3]

Behaviour and diet

The rinkhals has a varied diet. Its main prey is toads,[4] but it also eats small mammals, amphibians, and other reptiles.[6]

Rinkhals are unique amongst African cobras in being ovoviviparous.[3] They give birth to 20–35 live young, but as many as 65 young have been recorded.[4]

Venom

The venom of the rinkhals is neurotoxic and partially cytotoxic, and is less viscous than that of other African elapids.[3] When confronting a human, it generally aims its venom at the face. If the venom enters the eyes, it causes great pain.[6]

A polyvalent antivenom is currently being developed by the Universidad de Costa Rica's Instituto Clodomiro Picado[7]

Symptoms of a bite
Detail of head

Local symptoms of swelling and bruising is reported in about 25% (a quarter) of cases.[3] General symptoms of drowsiness, nausea, vomiting, violent abdominal pain, cramps and vertigo often occur, as does a mild pyrexial reaction.[3][6]

Defensive behaviour

If distressed, the rinkhals spreads its hood, showing its distinctive, striped neck. It is a spitting cobra, and can spray its venom up to 2.5 m. Its spitting mechanism is primitive and it has to rear up and fling its body forward to spray its venom. It is also known to fake death by rolling onto its back with its mouth agape.[8]

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.[6]

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References
  1. 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.
  2. The Reptile Database. www.reptile-database.org.
  3. S. Hunter (2000). "Venomous Reptiles".
  4. R. Mastenbroek (2002). "Rinkhals". Archived from the original on 2007-11-24.
  5. 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.
  6. B. Branch (1988). Field Guide to the Snakes and Other Reptiles of southern Africa. Struik, Cape Town.
  7. 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.
  8. BBC Earth Unplugged (2018-03-10), Rinkhals Snake Plays Dead | Deadly 60 | Earth Unplugged, retrieved 2019-02-16
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