Hognose

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Eastern hognose snake (Heterodon platirhinos) Heterodon platirhinos.jpg
Eastern hognose snake (Heterodon platirhinos)

Hognose snake is a common name for several unrelated species of snakes with upturned snouts, classified in two colubrid snake families and one pseudoxyrhophiid snake family.

Contents

They include the following genera:

The North American Heterodon species are known for their habit of thanatosis: playing dead when threatened.

Species

Genus Heterodon :

Plains hognose snake (Heterodon nasicus) Heterodon nasicus.jpg
Plains hognose snake (Heterodon nasicus)

Genus Leioheterodon :

Genus Lystrophis :

Nota bene : A binomial authority in parentheses indicates that the species was originally described in a different genus.

Description

The hognose snakes' most distinguishing characteristic is their upturned snout/rostral scale, which aids in digging in sandy soils by using a sweeping, side to side motion. They also like to burrow in masses of humus. Lieoheterodon species are known to dig up the eggs of lizards. [1]

Hognose snakes are extremely variable in color and pattern. Heterodon nasicus and H. kennerlyi tend to be sandy colored with black and white markings, while H. platirhinos varies from reds, greens, oranges, browns, to melanistic (i.e. black) depending on locality. They are sometimes blotched and sometimes solid-colored. Leiohetereodon geayi is a brown or tan colored snake with dark speckling on it. There are also many different morphs when bred in captivity.

Behavior

Juvenile hognose snake playing dead

When threatened, hognose snakes will hiss, flatten their necks and raise their heads off the ground like cobras. They sometimes feign strikes, but actual Heterodon bites are very rare. This behaviour has earned them local common names such as "puff adder", "blowing adder", "flathead", "spreadhead", "spreading adder" or "hissing adder". Note: For Heterodon, "puff adder" is a common name inconsistent with established usage. "Puff adder" is the accepted common name of Bitis arietans , an unrelated, dangerously venomous African species of viper, which incidentally does not flatten its neck in any threat display.

If this threat display fails to deter a would-be predator, Heterodon species often roll onto their backs and play dead, going so far as to emit a foul musk and fecal matter from their cloaca (in liquid form) and let their tongues hang out of their mouth, sometimes accompanied by small droplets of blood. If they are rolled upright while in this state, they will often roll back as if insisting they really are dead. It has been observed that the snake, while appearing to be dead, will still watch the threat that caused the death pose. The snake will 'resurrect' sooner if the threat is looking away from it than if the threat is looking at the snake. [2] [3]

They are rather timid snakes and commonly hide from predators by burrowing down into leaves, sand, etc.

Malagasy giant hognose snake (Leioheterodon madagascariensis) Leioheterodon madagascariensis.jpg
Malagasy giant hognose snake (Leioheterodon madagascariensis)

Diet

Heterodon are diurnal active foragers that typically consume their prey live without any constriction or body pinning, primarily relying on only their jaws to subdue their prey.

For most hognose snake species, the bulk of their diet is made up of rodents and lizards. Heterodon platirhinos is an exception, and specializes in feeding on toads, although other food items such as eggs and insects can make up as much as 50% of its diet.

In captivity

Hognose snakes are frequently found in herpetoculture. Heterodon nasicus is often considered to be the easiest to care for, and captive-bred stock is easily found. Heterodon platirhinos is also commonly found, but their dietary requirements can be a challenge for some keepers, and there is anecdotal evidence to suggest that feeding them a diet of exclusively rodents contributes to liver problems and a shortened life span. [4] Leioheterodon species are imported regularly from Madagascar, but they are not often bred in captivity and get much larger, so they can pose a set of different challenges for care. Lystrophis species are fairly new to the commercial reptile trade, and are now commonly bred in captivity, but can be some of the more expensive hognose snakes available. Some states, such as the state of Colorado, have strict laws on keeping the western hognose snake. It is considered a native species to Colorado, so it is protected by law. The law states that an individual can keep no more than four native snakes, and forbids the shipping, selling, and breeding of them in the state of Colorado.

Toxicity

Hognose snakes have mildly toxic venomous saliva and are frequently mistaken for the slightly more dangerous rear fanged snakes which possess grooved teeth and saliva intended for dispatching prey. Hognose saliva fails to meet the definition of a venom because they have no injection system and do not have behaviours typically seen in venomous animals. Indeed, the teeth of the hognose are smooth and strong without grooves and the mildly toxic duvernoy's secretions are produced by the Duvernoy's gland, well away from the unique evisceration fangs for which the genus is named. Hognose have never been formally documented using their saliva to kill prey, rather they kill by sawing and impaling prey, biting prey from the side rather than at the head to facilitate this process. Although it is possible that some day one or more species may provide data that alter the current classification of mildly toxic saliva to actual venom, the absence of any injection mechanism and indeed adaptations counter to venom injection will most likely always leave them difficult to classify. Hognose are perhaps best described as a transitional species with toxic saliva that is only produced during feeding, failing to fall into either of the classic recognisable categories of venomous or non venomous. Although their saliva is not likely to cause serious injury to humans in small amounts, should the toxic feeding saliva make its way into a cut in large enough amounts over an extended period of time the resulting swelling and localized tissue damage can be problematic in at least one species, H. Nasicus. Such occurrences are rare however as they are uninclined to bite, instead striking with mouth closed or playing dead. For these reasons they have been popular pets for more than 100 years despite the irritation experienced should they mistake their keeper's hand for food.

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<i>Boiga</i> Genus of snakes

Boiga is a large genus of rear-fanged, mildly venomous snakes, known commonly as cat-eyed snakes or simply cat snakes, in the family Colubridae. Species of the genus Boiga are native to southeast Asia, India, and Australia, but due to their extremely hardy nature and adaptability, have spread to many other suitable habitats around the world. There are 38 recognized species in the genus. According to the study done by Jiří Smíd regarding Old World cat snakes, the ancestor of the cat snake originated in Africa, from where it diversified and expanded to other countries. Despite this diversity however, the different species have very similar needs in terms of temperature and precipitation.

<i>Oxyrhopus petolarius</i> Species of snake

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<i>Boiga dendrophila</i> Species of snake

Boiga dendrophila, commonly called the mangrove snake or the gold-ringed cat snake, is a species of rear-fanged venomous snake in the family Colubridae. The species is endemic to southeast Asia. It is one of the biggest cat snake species, averaging 8–9 feet in length. It is considered mildly venomous. Although moderate envenomations resulting in intense swelling have been reported, there has never been a confirmed fatality.

<i>Ahaetulla</i> Genus of snakes

Ahaetulla, commonly referred to as Asian vine snakes or Asian whip snakes, is a genus of colubrid snakes distributed throughout tropical Asia. They are considered by some scientists to be mildly venomous and are what is commonly termed as 'rear-fanged' or more appropriately, opisthoglyphous, meaning their enlarged teeth or fangs, intended to aid in venom delivery, are located in the back of the upper jaw, instead of in the front as they are in vipers or cobras. As colubrids, Ahaetulla do not possess a true venom gland or a sophisticated venom delivery system. The Duvernoy's gland of this genus, homologous to the venom gland of true venomous snakes, produces a secretion which, though not well studied, is considered not to be medically significant to humans.

<i>Leioheterodon</i> Genus of snakes

Leioheterodon is a genus of harmless pseudoxyrhophiid snakes found only on the island of Madagascar. Three species are currently recognized. Common names include Malagasy hognose snakes, Malagasy brown snakes and Malagasy menarana snakes.

Lystrophis is the genus of tricolored South American hognose snakes. They mimic milk snakes or coral snakes with their red, black, and white ringed patterns.

<i>Heterodon</i> Genus of snakes

Heterodon is a genus of harmless colubrid snakes endemic to North America. They are stout with upturned snouts and are perhaps best known for their characteristic threat displays. Three species are currently recognized. Members of the genus are commonly known as hognose snakes, hog-nosed snakes, North American hog-nosed snakes, and colloquially puff adders.

<span class="mw-page-title-main">Eastern hognose snake</span> Species of snake

The eastern hog-nosed snake, is a species of mildly venomous rear-fanged snake in the family Colubridae. The venom is specifically adapted to amphibian prey and is harmless to humans. However, some people may have an allergic reaction, and experience local swelling and other symptoms. The species is endemic to North America. There are no subspecies that are recognized as being valid. This species prefers habitats with sandy soils and a combination of grass fields and forest edges. They come in many different colorations and have the identifiable upturned "snout". They can be found in captivity but are a relatively difficult species to keep due to a specialized diet of toads. As with other Heterodon species, they have a distinctive threat reaction of first bluffing by striking with a closed mouth and then pretending to die if this fails to deter the threat.

<span class="mw-page-title-main">Western hognose snake</span> Species of reptile

The western hognose snake is a species of snake in the family Colubridae. The species is endemic to North America. There are three subspecies that are recognized as being valid, including the nominotypical subspecies.

<i>Psammophis</i> Genus of snakes

Psammophis is a genus of snakes in the family Psammophiidae. The genus comprises 33 species, which are found in Africa and Asia. Psammophis are diurnal and prey on lizards and rodents which they actively hunt. All species in the genus are venomous, and the venom is considered mild and not dangerous to humans.

<i>Leioheterodon geayi</i> Species of snake

Leioheterodon geayi, commonly known as Geay's hognose snake, the Madagascan speckled hognose snake, and the speckled hognose snake, is a species of mildly venomous snake in the family Lamprophiidae. The species is native to southwestern Madagascar.

<i>Leioheterodon madagascariensis</i> Species of snake

Leioheterodon madagascariensis, the Malagasy, Madagascar or Madagascangiant hognose(snake), is a harmless species of pseudoxyrhophiid snake endemic to the island nation of Madagascar. The species is also found on the country's smaller islands of Nosy Be, Nosy Mangabe, and Nosy Sakatia, as well as on the Comoros archipelago, in the Mozambique Channel. It is thought, by some, to have been introduced to the Grande Comoro. Mature giant hognose snakes can measure between 130 and 180 cm (4 ft. to nearly 6 ft., or between 1-2 meters) in length, and be roughly the thickness of an average adult human's arm.

<i>Ithycyphus miniatus</i> Species of snake

Ithycyphus miniatus is a species of mildly venomous snake in the family Pseudoxyrhophiidae. The species is native to Madagascar.

<i>Xenodon</i> Genus of snakes

Xenodon is a genus of New World snakes in the subfamily Dipsadinae of the family Colubridae.

<i>Xenodon pulcher</i> Species of snake

Xenodon pulcher is a species of fossorial snake in the family Colubridae. It is found in southern South America.

<i>Micrurus mipartitus</i> Species of snake

Micrurus mipartitus is a species of coral snake in the family Elapidae. The species is native to Central America and northern South America. The red-tailed coral snake is common in agricultural areas in Colombia. Its highly neurotoxic venom is known to cause seizures in its prey by activating nerve proteins responsible for seizures within it.

Heterodon kennerlyi, also known commonly as the Mexican hognose snake, Kennerly's hog-nosed snake, and la trompa de cerdo mexicana in Mexican Spanish, is a species of snake in the subfamily Dipsadinae of the family Colubridae. The species is native to the southwestern United States and adjacent northeastern Mexico

<i>Xenodon dorbignyi</i> Species of snake

Xenodon dorbignyi, the South American hognose snake, is a species of snake in the family Colubridae. The species is native to southern South America. There are four recognized subspecies.

References

  1. ↑ Glaw, Frank; Vences, Miguel (2007). A Field Guide to Amphibians and Reptiles of Madagascar 3rd edition. Köln: M. Vences & F. Glaw Verlags GbR. ISBN   978-3-929449-03-7.
  2. ↑ Burghardt, G.M.; Greene, H.W. (1988). "Predator simulation and duration of death feigning in neonate hognose snakes". Animal Behaviour. 36 (November–December): 842–44. doi:10.1016/S0003-3472(88)80127-1. S2CID   54259559.
  3. ↑ Elting, Mary (1987). Snakes and other Reptiles (1 ed.). Simon & Schuster Children's Publishing. p.  5. ISBN   9780382337031 . Retrieved 8 January 2019.
  4. ↑ "Hognose.com: Eastern Hognose Species Description". Archived from the original on 2007-03-25. Retrieved 2007-03-09.
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