Morelia spilota harrisoni
Scientific Name: Morelia spilota harrisoni
Common Names: Papuan Carpet Python, Irian Jaya Carpet Python
Taxonomy
Morelia spilota harrisoni was traditionally known as the Irian Jaya Carpet Python, but in recent times, it has become more commonly referred to as the Papuan Carpet Python. This name change reflects the species’ geographic distribution and is now widely accepted. Like other carpet pythons, it belongs to the Pythonidae family. The subspecies was formally described by Raymond Hoser in 2000 and was named in honor of David Harrison, a prominent aviculturist and conservationist.
Description
Morelia spilota harrisoni is a medium-sized python native to the Indonesian province of Papua and Papua New Guinea. Adults generally reach lengths of around 1.5 to 2 m (5’ to 6’5”), with some individuals occasionally exceeding this size. Males tend to grow larger than females, with recorded lengths of wild specimens up to 2.6 m (8.5 feet) and weights up to 3189 g (7 lbs) (Natusch and Lyons, 2011).
In captivity, however, animals typically stay around 1300 – 2500 g (2.87 – 5.51 lbs), with similar lengths to those found in the wild.
Morelia spilota harrisoni typically has bronze to green-brown saddles, gradually getting darker towards the spine. Their stripes or sometimes patches on the sides are typically yellow to sand-colored with a black stroke. Many individuals have some striping down their back. That said, there’s a lot of variability in the appearance of this subspecies.
In the past, many imported animals were dark bronze to black with gray stripes, whereas imports today seem to be much brighter with yellow stripes; some animals almost resemble Morelia spilota cheynei. From the few field observations available, it is known that these lighter-colored animals are found in the vicinity of Domande to the western edge of the Merauke Regency in the Indonesian province of Papua. Conversely, animals observed around Port Moresby in Papua New Guinea tend to have darker and more bronze-colored variations. This suggests that animals imported in the past may have come from Papua New Guinea, whereas those imported today are from the Merauke area in the Indonesian province of Papua.
Newly hatched neonates exhibit different coloration, often displaying a reddish hue that fades as they mature.
In terms of behavior, Morelia spilota harrisoni is primarily terrestrial but also exhibits some arboreal tendencies, particularly in younger individuals. Like other subspecies of carpet pythons, they can be quite defensive as hatchlings but generally outgrow this nervous behavior as they mature and becoming quite docile. However, they retain a very aggressive feeding response, often striking at anything that moves when their enclosure is oepened at night, hoping to catch food.
Distribution
Morelia spilota harrisoni is the only subspecies of carpet pythons that resides exclusively outside of Australia, being uniquely endemic to the island of New Guinea. This subspecies inhabits both Papua New Guinea and the Indonesian province of Papua. Their range extends across the southern coastal regions, including the Trans-Fly area on both sides of the border, and the coastal areas around Port Moresby in Papua New Guinea.
Notably, there was a report of a specimen found at Pionerbivak on the Mamberamo River in 1920 by Koey. However, this specimen was mislabeled, and the locality is no longer considered valid.
These pythons are primarily found in proximity to coastal zones, thriving in tropical woodlands, savanna habitats, and grasslands, where they are most frequently encountered. They are absent from more densely forested and rainforest regions further inland. This distinct preference for open woodlands and savanna-type habitats sets them apart from other carpet python subspecies found in Australia. In terms of elevation, Morelia spilota harrisoni is typically found at low to moderate altitudes, with most individuals recorded from areas at or near sea level to around 300 meters above sea level. This distribution is characterized by a seemingly fragmented pattern, which may partly be due to gaps in collection data or unsuitable habitats in certain regions.
The presence of Morelia spilota harrisoni in specific areas like Merauke and the Central Province near Port Moresby highlights the localized nature of their distribution, with no recorded sightings north of approximately 7°S latitude.
Captive Care
Carpet pythons, in general, are very easy to care for and thrive well in captivity, making them ideal for both beginners and experienced keepers. While some hatchlings can be nervous and may strike when handled, they typically calm down with regular interaction. As they mature, they tend to outgrow this behavior and become quite docile. Adult carpet pythons are usually easy to handle and display a calm demeanor.
Cage Size
An enclosure of 120x60x60 cm (4’x2’x2’) is recommended for adults.
Substrate
Allspan Super, hemp bedding, coconut husk, or cypress mulch all work perfectly well. I prefer Allspan Super myself as it never molds and is super easy to spot clean.
Humidity
Carpet pythons are very forgiving when it comes to humidity and typically do not have problems shedding. I maintain around 50% humidity.
Heating
I have noticed that Morelia spilota harrisoni typically prefer a bit colder tempertures compared to other sub species of carpet pythons, and through monitoring their body tempertures over periods of time, I have observed that they always keep a core body temperture of 27°C (80.6°F).
I provide a heat spot of around 28-29°C (82-85°F) and keep the cool end of their enclosure at around 26°C (78.8°F).
Cycle
I keep light and heat on for 10 hours a day year-round. Nighttime temperatures depend on seasonal fluctuations and can go as low as 19°C (66.2°F) on the coldest nights during winter.
I offer my animals a cooling period from the end of November to the start of March. During this time, they experience colder nighttime temperatures and are completely without food.
Feeding
Carpet pythons are enthusiastic feeders and will prey on appropriately sized rodents and birds. I start hatchlings on mouse fuzzies or rat pinkies and switch to larger mice and eventually rats as they mature.
Most reptiles in captivity are unfortunately obese, and overweight snakes have become the norm. As a result, it can be challenging for new keepers to recognize what a healthy carpet python looks like. When viewed from above, you should see muscles on each side of the backbone, which itself should appear slightly sunken. This contrasts with a round back that lacks definition and tone. The tail, from the cloaca to the tip, should look square and flat rather than resembling a round, elongated balloon. The head should be large and square, tapering into a thin neck. In summary, the ideal condition of a carpet python resembles a Toblerone bar rather than a Coke bottle.
Obesity in carpet pythons, and reptiles in general, is the leading cause of cancer. Additionally, even a small amount of excess fat can accumulate around organs, leading to issues such as fatty liver disease and fatty heart disease.
Overweight males are less likely to impregnate females, while overweight gravid females are more likely to experience complications during egg-laying, such as egg binding (inability to lay eggs) or laying infertile eggs (slugs).
Because carpet pythons have a strong feeding response and are kept in enclosures where they do not get the same amount of exercise as in the wild, it is very easy to overfeed them. Like humans, a sedentary lifestyle combined with consuming more calories than are burned will cause overweight.
Following a strict feeding regime is crucial for a long and healthy life for your carpet python. Hatchlings can be fed weekly, while carpet pythons ready to move to new owners should be fed every 1-2 weeks. As yearlings, you can continue feeding bi-weekly, gradually extending the time between meals to three weeks as they near two years of age. When they reach three years, feed them every four weeks, and from four years onward, they should be fed around seven times a year.
Cycling carpet pythons and cooling them for 3-4 months a year without food gives their metabolism and overall system a much-needed break.
Breeding
Breeding carpet pythons is relatively simple, but for the best continuous results, you need to cycle them.
I live in Denmark, where winter occurs from December to February, making these the coldest months. Therefore, it makes sense to plan my cooling period during these months. If you experience winter at a different time of the year, adjust accordingly.
I ensure the ambient temperature at night drops to around 19°C (66°F). This is weather-dependent, but it’s my target temperature for the coldest nights. I achieve this by using smart thermostats for ambient heat, that automatically drop at night and increase in the morning.
If you have trouble breeding carpet pythons, it’s often because they are kept too warm. I’ve found that some individuals breed well even at warmer temperatures, whereas others need to experience these colder conditions.
In mid-November, I feed my carpet pythons their last meal of the season, allowing them to defecate before entering the breeding season.
In early to mid-December, I introduce males to females by moving them into the females’ enclosures. I let the males stay for 1-2 weeks, then give them a few days’ break before reintroducing them to the females.
If we experience nights with heavy snow or strong winds, I ensure the males are with the females, as the low atmospheric pressure triggers breeding responses in the snakes.
I continue introducing the males to the females until I’m certain the female is gravid (she looks large and round in the last third of her body). This usually occurs around February. In February or March, the female will shed, which is called the pre-lay shed, indicating she is about to lay her eggs. The eggs are usually laid 30-60 days after the pre-lay shed. 30-40 days is most common, but some females may take longer, which is normal.
After the female has laid her eggs, I place them in an incubation box and then in the incubator. I use plastic boxes with a grid in the middle. Beneath the grid, I have tap water, and I lay the eggs on the grid. The box is sealed with a lid, which has four small holes, one in each corner.
I incubate the eggs at around 31°C (88°F), maintaining as constant a temperature as possible. After about 60 days, the eggs will start to hatch. About a week before hatching, the eggs will begin to dent, indicating the hatch time is near.
I remove the hatchlings as soon as they are fully hatched and place them in separate boxes with a misted paper towel, and place the boxes in a hatchling rack. I provide the hatchlings with a heat spot of around 28-30°C (82-86°F), turned on for 10 hours a day like the adults, and completely off at night.
Typically, after about a month, the hatchlings will shed, and I will attempt to feed them with a fuzzy mouse or rat pinky. If most of the clutch has shed but some individuals haven’t, I will try to feed them before they shed, and they usually take the food and shed faster.
Projects
Axanthic
Axanthic affects the production of xanthophores and erythrophores, the cells responsible for yellow and red pigments, respectively. This mutation reduces both yellow and red pigmentation, resulting in an almost monochromatic appearance with shades of black, white, and gray.
It was initially believed to be a recessive trait. However, as some heterozygous animals display a gray coloration, almost to the degree of homozygous individuals, this suggests the trait may instead be incompletely dominant.
The axanthic gene in Morelia spilotta harrisoni was proved out in Poland by Krzysztof Nowak from Awesome Reptiles in 2008. Nowak paired a WC male with a CB female from Marc Mense. Both snakes appeared normal but were noticeably light-colored. Upon breeding the offspring, Nowak discovered visual axanthics among them, thereby demonstrating that the WC male was heterozygous for the axanthic gene.
Interestingly, Raphael Doll from Striking Pythons unexpectedly proved another wild-caught male to be heterozygous for axanthic in 2023, further confirming the presence of the axanthic trait in the wild population.
I have always been fascinated by the axanthic look and therefore work on several different line breeding projects related to this trait.
Hypo
The presence of the hypo mutation in Morelia spilota harrisoni has only recently gained recognition, but the history dates back further than commonly thought. As previously mentioned, Krzysztof Nowak proved the axanthic mutation, using founder animals that were notably light-colored. It turns out that the CB female Nowak acquired from Marc Mense was actually a hypo, which means that the axanthics Nowak produced were, in fact, hypo axanthics. At the time, axanthic Morelia spilota harrisoni had never been seen, so this was not immediately understood.
Marc Mense was working with granites from Piet Nuijten, who had proven that mutation. Mense paired an animal with a WC hypo female, resulting in offspring, from which Nowak purchased a female he then used to produce double heterozygous hypo axanthics.
In 2010, Raphael Doll from Striking Pythons bought two visual axanthics and three heterozygous axanthics from Nowak. One of the males was a hypo axanthic, and he later became one of the foundational animals for most of the axanthic Morelia spilota harrisoni in captivity today. Interestingly, Raphael also proved this same male to be heterozygous for granite.
However, the story of the hypo mutation goes even further back. In 2003, Raphael Doll obtained a female from Daniel Potier of Reptibel. The sire of this female was hypo, suggesting that the hypo mutation entered Europe through WC imports in the 1990s.
I purchased a pair of heterozygous axanthic CB13 Morelia spilota harrisoni from Raphael Doll. These were offspring from the hypo axanthic het granite CB10 male from Nowak. The female exhibited brighter colors than the male, and what you would normally see in Morelia spilota harrisoni.
In 2017, I paired these two animals and kept a possible heterozygous axanthic female due to her exceptionally bright and gray coloration as a hatchling, showing signs of visual heterozygous. In 2018, I bred the CB13 heterozygous axanthic animals again and produced a visual axanthic male, which I kept.
In 2023, I bred the CB18 visual axanthic male with the CB17 heterozygous axanthic female and produced some extremely bright, jaguar-looking axanthics.
Although I sold all the animals, I received a photo from one of the new owners. The animal illustrated was nearly a year old at the time the photo was taken, and it had already lost a significant amount of dark pigmentation.
In 2024, I bred an axanthic granite CB19 male from Raphael Doll with my heterozygous axanthic CB13 female, also from Raphael Doll, and produced visual hypo axanthics, also known as ghosts.
All animals in this clutch were brighter than typical axanthics and unlike any other specimens I’ve produced, suggesting they carry the hypo mutation in some form. The axanthic granite male, the sire of the clutch, was very bright in his younger years but has gained more black pigmentation over time, while his gray colors remain extremely bright. The dam is much brighter than the CB13 male from the same clutch as her, and much brighter than a normal-looking harrisoni, suggesting she also carries the mutation. This would mean that both parents carry the mutation, explaining why the whole clutch came out brighter than normal, with some outliers being more extreme, indicating they might actually be supers, suggesting the mutation is incompletely dominant.
The gene seems to function like a highlighter gene mixed with hypo. Animals in their normal form are brighter but don’t necessarily lack a lot of black pigmentation like caramel or hypo coastals, though it seems some individuals do. In its super form, however, animals will be extremely bright and lack black pigmentation. Hatchlings are born very bright but will go through a dark phase within a few sheds, then brighten up and start lacking black pigmentation within 6-12 months. This development will continue over the following year.
We are only recently starting to piece the puzzle together and understand the mutation through previous and ongoing breedings. Where animals in the past were sold as bright normals, we now understand that they actually carried the hypo mutation. Recent breedings suggest that there is a super form, making the gene incompletely dominant as previously mentioned. This belief is supported by Raphael Doll, who is also actively working with the mutation.
Granite
Granite is a recessive genetic mutation that was first discovered and produced by Piet Nuijten from Holland around year 2000.
Nuijten bought a pair of imported animals around 1994. Three years later he bred the pair and hatched 16 babies from which he kept a male and two females. When the holdbacks were three years old he attemted to breed them together. One of the females laid 11 eggs. When they hatched, it turned out that four of them were granites.
This mutation is characterized by a distinctive appearance where the typical pattern is disrupted into a unique pattern of individually pigmented scales, resembling granite rocks. The regular pattern is replaced with a series of darker and lighter spots, giving the snake a mottled look. Furthermore they seem to be more docile than non granites.
Clown Stripe
In 2024, I hatched four clown stripe axanthics from a clutch of eleven hatchlings.
The breeding involved a pair of CB17 striped axanthics that I produced from my CB13 heterozygous axanthic animals.
Interestingly, I bred the same pair the year before but did not produce any clown stripes. The genetics behind this trait are not yet fully understood, but I believe it to be a polygenic mutation. Further breeding will be needed to clarify the inheritance pattern and establish whether it is indeed polygenic.
IMG
IMG (Increased Melanism Gene) is a genetic trait that causes an increased production of melanin as the animal ages, resulting in a darker overall appearance.
In 2014, Eric Burke from EB Morelia bred a bright male with an IMG female (Poison Ivy) and produced normal-looking babies. However, as these babies aged, they developed more melanin, which indicated that the mutation is either dominant or incomplete dominant.
I was fortunate to acquire a CB11 IMG male and immediately added him to my collection. In 2024, I bred him with a CB18 striped reduced pattern female. Unfortunately, most of the eggs were lost, but two babies hatched. One had a kink, but the other, a female, turned out perfectly. It will be interesting to observe how she develops over time.
Besides my CB11 IMG male, I also have a WC14 female. I first saw this female at the importer back in 2015, and she stood out, although she looked quite different from her current appearance. Initially, she was a darker bronze color, but today she is jet black with gray stripes. Someone else bought her from the importer at that time, but I was fortunate enough to acquire her years later.
In 2024 I paired my axanthic granite CB19 with her a got a clutch of 7 babies.
I hope to breed the two IMG animals together in 2025.
Striped animals/Tiger
I have a passion for striped animals and have consistently line bred for this trait, enhancing the striping with each generation. While I simply refer to them as striped animals, they are also commonly known as ‘tigers.’ By breeding animals with some degree of striping, it is often possible to produce offspring with even more pronounced striping. If you pair a highly striped animal to a non striped animal, you will produce highly striped outcome.
This trait is polygenic, meaning it is influenced by multiple genes rather than a single gene. As a result, polygenic traits exhibit a range of expressions and have complex inheritance patterns due to the cumulative effects of several different genes.
Conservation Status
IUCN Red List: Least concern
CITES: Appendix II
Status: The trade and import of Morelia spilota harrisoni have been significantly influenced by its demand in the international pet market. While Indonesia is the only country that permits the legal harvest and export of wild carpet pythons, the management of this trade has faced numerous challenges. One prominent issue involves the manipulation of harvest quotas.
Legally, carpet pythons can be harvested from the Indonesian provinces of Papua and West Papua. However, in practice, these snakes are predominantly collected from Papua, as they are not found in West Papua. Despite this, the national harvest quota has historically been divided equally between these two provinces. This allocation has led to a consistent overharvest in Papua since at least the year 2000. The discrepancy arises because traders have often circumvented the intended distribution by transporting pythons from Papua to be falsely documented as originating from West Papua. This misrepresentation allows for a greater number of snakes to be legally exported than permitted by the regional quotas.
Given these challenges, it is crucial to continue monitoring the population and trade dynamics of Morelia spilota harrisoni. Awareness and education about the species’ status and the importance of ethical practices in the pet trade can help mitigate the impact of overharvesting. Conservation efforts should focus on ensuring that these pythons remain a viable and thriving part of their natural ecosystem.
Gallery
Written by Paul Sørensen DKPythons