Pseudechis porphyriacus

Geographic Range

Red-bellied black snakes, Pseudechis porphyriacus , are found in the Australian region along the east coast of Australia. This species reaches as far northeast as Cairns, Queensland, stretches as far southwest as Adelaide, South Australia and as far south as Melbourne, Victoria. Red-bellied black snakes follow the coast line from Cairns all the way through Brisbane, into New South Wales and Victoria. In the states of New South Wales and Victoria red-bellied snakes begin stretching westward from the eastern coastline moving nearly 700km inland in New South Wales. In Victoria, red-bellied black snakes' range reaches inland following the border between Victoria and New South Wales. This species is limited to two northeastern isolated pockets and an isolated pocket in the southeast city of Adelaide. Once the species' range reaches Brisbane, these snakes can be found continuously to Melbourne.

• Biogeographic Regions
• australian australian
  • native native

Habitat

Red-bellied black snakes are often found in wet environments such as swamps or lagoons. They are less commonly in forests among tall, thick patches of ground vegetation. Being an ectothermic species, spaces with direct sunlight are important for their habitat. Therefore, warm grassland areas are another ideal habitat. When found in developed rural areas, they tend to live near drainage ditches. Elevations have not been reported for these snakes.

• Habitat Regions
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest

• Aquatic Biomes
• rivers and streams

• Wetlands
• swamp swamp

• Other Habitat Features
• agricultural agricultural

Physical Description

Red-bellied black snakes reach lengths of 1.5-2.5 m (average 2.0 m). Males are slightly larger, though no measures are published to support this. Females have a greater widening of their of their mouth due to a skeletal difference between the hinge mechanism. Red-bellied black snakes acquired their common name by the bright red scales that cover the lowest lateral and outer ventral scales. At the central part of their underside, these bright red scales fade into softer red tones. The rest of the body scales are smooth, glossy, and black. Red-bellied black snakes do not have a strong physical distinction between their neck and head. Juveniles of this species do not differ from adults in appearance, except for in size.

This species is venomous.

By appearance, this species can be confused with blue-belled black snakes Pseudechis guttatus , as they are similar in length and also have smooth, glossy, and black scales. These two species are distinguished by color differences in their scales at the central ventral side.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry
• venomous venomous

• Sexual Dimorphism
• male larger

Development

Red-bellied black snakes are viviparous, giving birth to a sac of 5-18 live offspring. These offspring are able to remain in the sac for up to two days after birth.

Red-bellied black snakes emerge from the sac at an average length of 23cm and a weight of 11.1g. Males reach sexual maturity at 19 months, while females are mature at 31 months. This species grows at a rather rapid rate within the first year and have a weight increase of 18-fold and a tripling in length. On average, red-bellied black snakes reach 77cm in length and 200g in weight after 14 months. Males are 111cm, on average, at sexual maturity.

Similar to other snakes, red-bellied black snakes continue to grow throughout their life and shed their skin periodically to allow for growth.

• Development - Life Cycle
• indeterminate growth indeterminate growth

Reproduction

Red-bellied black snakes are polygynandrous, mating during the spring season. During the mating season, males will travel up 1220 meters a day to find a suitable mate, while females make far less movement. When multiple males encounter the same female for mating they will engage in combat and the females will chose the winner.

Mating involves a specific form of tactile communication with this species. One male will run its body along that of the female and may even begin to hiss or bite at the female if the male becomes excited. The female will show acceptance to mating by elongated her body and allowing the male to then align his body with hers.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Red-bellied snakes will breed once yearly. These snakes typically mate in the Australian spring, October to November, but have been documented mating as early as late winter (July-September). Females' gestation period lasts 4-5 months. After giving birth to 5-18 young, females abandon their offspring. At birth, the offspring weigh 10.1-11 g. This species gives birth to live young that will reach sexual maturity in two to three years for females. Males reach sexual maturity at an average length of 111 cm and an age of 19-24 months.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• sexual sexual
• viviparous viviparous

Red-bellied black snake females protect their young pre-birth by decreasing their movements. This reduced activity ensures that they do not fall victim to predators. Females will move to secure food for themselves and their offspring. Like most snakes, neither sex cares for the young post-birth. Indeed, males have no part in taking care of their partners after mating has taken place.

• Parental Investment
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

The longest recorded lifespan for this species is 11.6 years while in captivity. There is no record of their lifespan in the wild.

Behavior

Red-bellied black snakes have been studied as a rather active species of snakes. One individual was recorded 420 meters away from its release site, 24 h after release. They are diurnal, which has been attributed to increased activity at higher body temperatures of 28-31 degrees Celsius. Red-bellied black snakes are more active than other snake species during the winter months.

Red-bellied black snakes are ground-dwelling but have been observed hunting underwater or even submerging themselves to escape predators.

There is little research describing if they travel in pairs or groups. Group activity is limited to gravid females staying in groups of up to six during the late stages of gestation.

• Key Behaviors
• terricolous
• natatorial natatorial
• diurnal diurnal
• motile motile
• solitary solitary

Home Range

Red-bellied black snakes are active and can move hundreds of meters over the course of about a week. They are typically located within 100 m of lagoons or streams. Radiotelemetry studies reported home ranges of 0.02 - 110 ha, with males moving more than females during the breeding season. Territory sizes have not been reported.

Communication and Perception

Red-bellied black snakes have two main uses for communication, mating and combat. When the males search for a females, they may encounter other males that could be chasing the same female. Here, the two will engage in combat. Combat is conducted by the males elongating and spreading their necks, rearing up their forebodies and then intertwining themselves by using a twisting motion to interlock their necks. Combat continues from this point by both males remaining outstretched while pushing against one another in the attempt to be chosen as the winner by the female. Combat can range in time from only a few minutes to half an hour.

Mating involves a specific form of tactile communication with this species. One male will run its body along that of the female and may even begin to hiss or bite at the female if the male becomes excited. The female will show acceptance to mating by elongated her body and allowing the male to then align his body with hers.

In general snakes possess specific receptors for sensing heat, meaning they are able to sense the presence of prey or predators without having to physically see them based of radiant heat.

• Communication Channels
• visual visual
• tactile tactile
• chemical chemical

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• infrared/heat infrared/heat
• tactile tactile
• chemical chemical

Food Habits

Red-bellied black snakes are a carnivorous, opportunistic feeders. Their food ranges from lizards, frogs, snakes, including their own species and aquatic species such as fish and tadpoles. Red-bellied black snakes specialize in eating frogs. While this species is not an aquatic one, these snakes will hunt in water, either by submerging their neck and head to hunt or using their tail and lower extremities to unsettle the patches in the water to find prey. In some cases, snakes will submerge themselves completely to catch prey. They often return to land with the captured prey, but have been observed consuming their prey while still submerged.

In captivity, this species has been recorded consuming their prey before their venom has taken full effect. They have also been documented as fast eaters. Wild red-bellied black snakes are assumed to have the same feeding habits as there have been observations of captured members of this species regurgitating live frogs, which means their venom was not used on this prey before consumption.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • piscivore piscivore

• Animal Foods
• amphibians
• reptiles
• fish

Predation

Adult red-bellied black snakes have two main predators: humans and feral cats . Juveniles face a wider range of predators such as carnivorous birds, such as kookaburra ( Dacelo species) , other snakes, frogs, and redback spiders ( Latrodectus hasselti ). An indirect predator of the red-bellied black snakes is cane toads ( < Rhinella marina >). When these snakes attempt to consume the invasive toads, toads' toxins are strong enough to kill the snakes.

These snakes can deter predators because they are venomous.

Ecosystem Roles

This species is a predator and acts as a form of pest management by consuming animals such as rats and mice.

This species has high potency venom and has been given the nickname "death adder" even though they have never been recorded to cause human death.

There is a tapeworm parasite known as Ophiotaenia gallardi that uses red-bellied black snakes as a host.

Economic Importance for Humans: Positive

There are no positive impacts of red-bellied black snakes on humans.

Economic Importance for Humans: Negative

Venomous red-bellied black snakes have a negative impact on humans when they bite humans. despite the common name "death adder," Australia reports no human deaths due to these snake bites. The species is said not to be aggressive unless provoked. If bitten, humans should seek immediate treatment.

• Negative Impacts
• injures humans
  • bites or stings
  • venomous venomous

Conservation Status

Red-bellied black snakes are marked as a species of "Least Concern" under the IUCN Red List. This species has no special status for the US Federal list, CITES, and State of Michigan list.

A concern for this species is the invasion of cane toads ( Rhinella marina ). In parts of New South Wales where cane toads have invaded, there has been a recorded decline in red-bellied black snake populations. However, the cane toads are not found in Victoria, meaning they have had no impact on the populations there. Further, the impact of these toads may not be permanent; in areas where the toads have been present for an extended amount of time, the decline in red-bellied black snakes has stopped. This suggest that the snakes are adapting to this new invasive species and learning to avoid eating the toads.

Although protections for this particular species are not in place, all Australian snakes are a protected group under the Wildlife Act 1975. Under this act, attempting to kill a snake is illegal and is more likely to cause injury to the human.

Additional Links

Encyclopedia of Life

Contributors

Matthew Palamara (author), Radford University, Layne DiBuono (editor), Radford University, Lindsey Lee (editor), Radford University, Kioshi Lettsome (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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