Common names for Deinagkistrodon acutus include Chinese moccasin, hundred-pacer, sharp-nosed viper, and snorkel viper. The venom of D. acutus contains a potent neurotoxin that is potentially lethal to humans. Its large, hinged fangs allow for effective delivery of large quantities of venom. Immediate bite symptoms include severe localized pain and bleeding. Several proteases in the venom are responsible for local tissue damage and immediate hemorrhagic symptoms. These symptoms are followed by swelling, blistering, necrosis, and ulceration. Systemic symptoms, which often include heart palpitations, may occur suddenly and soon after being bit. Deinagkistrodon acutus is responsible for many of the snake-bite related moralities in southern China and Taiwan. Fortunately, researchers have been able to manufacture a monovalent antivenin to administer to bite-victims. However, the antivenin is only effective if taken within a few hours of the bite.
Deinagkistrodon acutus has no known predators. However, it is vulnerable to attack by conspecifics and ophiophagous (i.e., cannabalistic) snakes. Anti-predator adaptations include cloacal discharge where the contents of the cloaca are expelled in a fine stream or spray, sometimes ejected a considerable distance. In addition, pit-vipers assume a "body bridge" position in which a portion of the body is raised in the direction of a predator. This species' quick-strike capabilities and venomous bite likely deter potential predators and reduce predation risk.
Known Predators:
Deinagkistrodon acutus adults range in length from 910 to 1210 mm, with the largest specimen on record measuring 1545 mm. Although D. acutus is a relatively large and stout-bodied snake, it is relatively smaller than many of the species the genus Agkistrodon. They possess a protuberant, upturned snout. Pit-vipers bear a pit on each side of the face, between the nostril and the eye, which contains a temperature sensitive pit organ. The pit organ allows animals to sense thermal radiation at specific wavelengths and may also be used in thermoregulation and predator avoidance. Each side of the body is patterned with a prominent series of 15 to 23 pairs of large dark triangles, with a base color of gray or brown. The venter is whitish and speckled with conspicuous gray and black spots that vary in size and shape. Adults have darker coloration than juveniles, which have yellowish tails until adulthood. Adult coloration bears a striking resemblance to that of southern copper-heads found in the United States. Its upturned snout, dark triangular body patterning and strongly tuberculate-keeled scales are relatively unique characteristics that help distinguish it from similar species. Deinagkistrodon acutus is sexually dimorphic, as males have longer tails and females have longer body lengths.
Range length: 1545 (high) mm.
Average length: 910 to 1210 mm.
Other Physical Features: heterothermic ; venomous
Sexual Dimorphism: female larger
There is little information available regarding the average lifespan of Deinagkistrodon acutus. In the wild, maximum lifespan has been estimated at 20 years, and the oldest known captive individual lived for 16 years and 3 months.
Range lifespan
Status: captivity: 16 years and 3 months (high) years.
Typical lifespan
Status: wild: 20 (high) years.
Sharp-nosed pit vipers prefer moist, shaded habitats usually in montane forests and foothills under 1200 m but have been documented at elevations of up to 1400 m. They occur among rocks, in vegetation along valley streams, and near farm houses where they have been known to hide in dark places in search for rodents.
Range elevation: 200 to 1400 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: forest ; mountains
Other Habitat Features: agricultural
Deinagkistrodon acutus can be found in Southeastern China in the provinces of Anhwei, Chekiang, Fukien, Hunan, Hupeh, Kiangsi, Kwangsi, Kwangtung, Kweichow, extreme southeastern Szechwan, and possibly Yunnan. This species also occurs in northern Vietnam, and central and southern Taiwan.
Biogeographic Regions: oriental (Native )
Deinagkistrodon acutus is carnivorous. Their general diet consists of birds, rodents, lizards, frogs and toads. After large meals, snakes may remain motionless for days.
Animal Foods: birds; mammals; amphibians; reptiles
Primary Diet: carnivore (Eats terrestrial vertebrates)
Deinagkistrodon acutus preys upon small animals such as birds, rodents, lizards, frogs and toads. As a result, it may help control certain agricultural pest species (e.g., small rodents) throughout its geographic range. Known parasites of this species include pentastomid endoparasites and one species of spiny-headed worm.
Commensal/Parasitic Species:
D. acutus has both commercial and medicinal importance in China. Its venom has been used for centuries as a traditional remedy for rheumatiod arthritis and pain in tendons and bones. More recently, the venom's anticoagulation attributes have been incorporated in hemostatic and thrombolytic drugs, which are widely used to prevent harmful blood clotting in stroke victims.
Positive Impacts: source of medicine or drug
Deinagkistrodon acutus is known for entering homes in search of food and its bite is lethal to humans.
Negative Impacts: injures humans (bites or stings, venomous ); household pest
Optimal temperature for hatching in Deinagkistrodon acutus ranges from 22.6 C to 36.5 C, with an average of 27.6 C. Hatchlings measure about 21 cm in length. First molt tends to occur ten days after hatching. The number of molts per year is usually between three and four, but can be as many as five depending upon environmental conditions and food availability.
Although Deinagkistrodon acutus is not listed on the IUCN's Red List of Threatened Species, China has listed this species as "vulnerable". Many populations throughout China have declined due to over-exploitation and habitat destruction. As a result, China began a captive breeding program that, so far, has been successful in decreasing commercial exploitation of wild populations.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Pit organs, which are found in all pit vipers, help Deinagkistrodon acutus detect specific wavelengths of infrared heat emitted by prey and potential predators. Pit organs are also thought to help in thermoregulation. Fibers innervating pit-organ receptors are completely insensitive to tactile stimuli but visual and infrared stimuli allow the snake to locate endothermic prey such as small rodents, especially in the dark. Like many other snakes and lizards, the tongue of D. acutus is used for olfactory perception. Vomeronasal functioning is essential for the initiation of male courtship of reproductively active females during breeding season.
Communication Channels: visual ; chemical
Other Communication Modes: pheromones ; vibrations
Perception Channels: visual ; infrared/heat ; acoustic ; chemical
Deinagkistrodon acutus is polygynandrous. Males chase females during courtship and use olfaction to investigate various parts of the female's body. Once a male has secured his mate and their heads are aligned, their tails being to wrap around each other and vibrate continuously. Mating in D. acutus can last from 2 to 6 hours.
Mating System: polygynandrous (promiscuous)
Little information is available concerning the mating behavior of Deinagkistrodon acutus. Mating has been observed from March through May and again from September through November. Gestation length ranges from 20 to 35 days. Most females are reproductively mature by 36 months of age, and clutch sizes range from 5 to 32 eggs, with an average of 20. Hatchlings range in mass from 6 to 14.5 grams.
Breeding interval: Deinagkistrodon acutus breeds twice yearly.
Breeding season: Deinagkistrodon acutus breeds from March through May and again from September through December.
Range number of offspring: 5 to 32.
Average number of offspring: 20.
Range gestation period: 20 to 35 days.
Average age at sexual or reproductive maturity (female): 36 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; fertilization ; oviparous
Deinagkistrodon acutus is oviparous and lays about 20 eggs at a time. During incubation, mothers coil themselves around their eggs for approximately 20 days, after which hatchlings emerge and are completely independent of parental care.
Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female)
Deinagkistrodon is a monotypic genus[4] created for the venomous pit viper species, Deinagkistrodon acutus, which is endemic to Southeast Asia.[2] No subspecies are currently recognized.[5]
Deinagkistrodon acutus is light brown or greyish brown dorsally, with a series of dark brown lateral triangles on each side. The two pointed tops of the two opposite triangles meet each other at the mid-line, forming a series of about 20 light brown, squarish blotches on the back. A row of large black spots extends along each side near the belly. The top and upper sides of the head are uniformly black, with a black streak from the eye to the angle of the mouth. D. acutus is yellowish ventrally, spotted with dark brown. The young are much lighter than the adults with essentially the same pattern. The head is large, triangular, with an upturned snout. The body is very stout. The tail is short, ending in a compressed, pointed slightly curved cornified scale. The top of the head is covered with nine large shields. The dorsal scales are strongly and tubercularly keeled. The subcaudals are mostly in pairs, some of the anterior ones are single. This stout snake, usually between 0.8 and 1.0 metre (2.6 and 3.3 ft) in total length (including tail), reaches a maximum total length of 1.57 metres (5.2 ft) in males and 1.41 metres (4.6 ft) in females.[6] The largest specimen on record measured approximately 1.549 metres (5.08 ft).[7]
Common names for D. acutus include sharp-nosed viper, snorkel viper, hundred pacer,[8] Chinese moccasin,[9] Chinese copperhead,[10] five-pacer, hundred-pace snake, long-nosed pit viper, sharp-nosed pit viper,[11] hundred-pace pit viper.[12] The snake has been an object of veneration by indigenous Taiwanese peoples.
Deinagkistrodon acutus is found in southern China (Zhejiang, Fujian, Hunan, Hubei, Guangdong), Taiwan, northern Vietnam, and possibly Laos. The type locality was not included in the original description. It was later given as "Wusueh [Wu-hsueh], Hupeh Province, China" by Pratt (1892) and Pope (1935). Listed as "Mountains N. of Kiu Kiang" in the catalogue of the British Museum of Natural History.[2]
The species D. acutus inhabits high, forested mountains up to 1,350 metres (4,430 ft), but has also been found in low coastal regions (100 metres (330 ft)). It prefers lower mountain slopes or rocky hills with small valleys.[6]
The diet of D. acutus consists of small mammals such as rats and mice, birds, toads, frogs and lizards. Chinese herpetologist Er-mi Zhao reported a specimen of a total length of 1.04 metres (3.4 ft) and weighing 600 grams (1.3 lb) having eaten a specimen of Rattus rattus of a total length of 51.5 centimetres (20.3 in) and a weight of 530 grams (1.17 lb).[6]
As one of the few oviparous pit vipers, D. acutus can lay up to 24 eggs, which may be retained during initial incubation, an adaptation that shortens post-deposition incubation time. However, it generally only deposits 11 or 12 eggs from June to August. Egg size is 40–56 x 20–31 mm (about 2 × 1 in). Hatchlings are lighter and more vividly patterned than the adults, but this darkens considerably with age.[8][6]
Dangerous animals often have exaggerated reputations and the species D. acutus is no exception. The popular name "hundred pacer" refers to a local belief that, after being bitten, the victim will only be able to walk 100 steps before dying. In some areas, it has even been called the "fifty pacer" or, in extreme examples, the "five-step snake." This often causes bite victims to needlessly amputate or burn bitten fingers or limbs, resulting in further complications like the loss of the amputated body part or gangrene. Nevertheless, this species is considered dangerous, and fatalities are not unusual. An antivenom is produced in Taiwan.[8][13]
Brown (1973) mentions a venom yield of up to 214 mg (dried) and LD50 (toxicity) values of 0.04 mg/kg IV, 4.0 mg/kg IP and 9.2–10.0 mg/kg SC.[14] The venom contains at least four hemorrhagins Acutolysin A, B, C[15] and D.[16]
According to the US Armed Forces Pest Management Board, the venom is a potent hemotoxin that is strongly hemorrhagic. Bite symptoms include severe local pain and bleeding that may begin almost immediately. This is followed by considerable swelling, blistering, necrosis, and ulceration. Systemic symptoms, which often include heart palpitations, may occur suddenly and relatively soon after the bite.[9] Because of its body size and large hinged fangs which permit effective delivery of large quantities of venom, victims bitten by this snake should be treated accordingly.
The venom of this species is commonly used for research purposes. Researchers have found that this venom contains protease activity, meaning it attacks and degrades intra- and extracellular proteins.[17] If injected into mice, within 2 hours the venom begins a process known as mesangiolysis (the degeneration and death of cells that line the inner layer of the glomerulus and regulate glomerular filtration in the kidney).[17] Eventually, the kidneys no longer function and the mouse dies.[18]
When controlled, the venom has some clinical application. D. acutus snake venom contains a protein called ACTX-6.[19] This protein was shown to induce apoptosis (cell death) in isolated cancer cells through Fas pathway activation.[19] Fas is a protein that becomes a death receptor in the cellular membrane. When activated, Fas turns on what is called a "caspase cascade".[20] This pathway is made up of a series of proteins called initiator and executioner caspases. Initiator caspases help form an apoptosis initiation factor that eventually activates executioner caspases (see figure 3). Executioner caspases go on to "digest" the cell from the inside out. They cleave cytoskeleton filaments and DNA until the cell completely implodes.[20]
Deinagkistrodon acutus venom has been used in traditional Chinese medicine for centuries to extract antivenin that is successfully used to treat snakebites.[21][22] Different parts of the snake are also prescribed to help alleviate ailments known as "wind diseases".[21] Because these snakes move so quickly, substances from their bodies are thought to easily treat these fast-moving "wind" syndromes. D. acutus is currently used in patients with arthritis, leprosy, tetanus, boils, and, as previously mentioned, tumors.[23] The same qualities that make snakes flexible, capable of regenerating skin, and able to inflict paralysis could be transferred to human conditions if applied medicinally.[24] The vipers are prepared by cooking the flesh of the headless body, grinding a paste of snake ash and mixing it with honey, drying the snake and compacting it into a powder, or even injecting their venom intravenously.[24] Although these practices are common in Chinese medicine, no current studies have affirmed the effectiveness of these treatments. Whether these "cures" simply have a placebo effect or actually heal the patients is not known.
Deinagkistrodon is a monotypic genus created for the venomous pit viper species, Deinagkistrodon acutus, which is endemic to Southeast Asia. No subspecies are currently recognized.
