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By Anders Nielsen, Ph.d.
Pythons are non-venomous constrictors found in tropical and subtropical Asia, Africa, and Australia. They were introduced into USA, South America, and Europe as pets. In Everglades, Florida, pythons have escaped captivity and have become a nuisance because they are far too many.
Pythons are ambushers and have a forked tongue that helps them detect odor from potential prey. The responsible organ is well known among herpetologists and is called the Jacobsen's or vomeronasal organ. Pythons strike with incredible velocity and kill their prey by constriction. That is, the caught animal die from asphyxiation, which is the same as suffocation.
A scientific study (Ayers et al. 1997)2 found that large body size in combination with a coiled posture slows the cooling rate and positively affects the snake's ability to detect and capture potential prey. If you encounter a coiled python, it may be preparing for its next meal.
It is well known that invasive species may pose a particular risk for ecosystems. A journal paper by Reed (2005)1 noticed that potential invasive species, such as ball pythons and reticulated pythons, may specifically damage areas with many endangered and threatened animals.
According to the media, pythons are invading the ecosystem of Everglades National Park. Scientists claim that the problem is exaggerated, and that the reported numbers of constrictors in Everglades National Park is much smaller than postulated.
University of Florida keeps a record on how many pythons are removed from Everglades annually. Counting complete populations is impossible.
Females delay reproduction until they have enough energy to breed a large clutch of eggs. Therefore, in periods with plenty of food, pythons can reproduce in vast numbers. In fact, the proportion of pythons reproducing each year is tightly connected to prey availability (Shine & Madsen (1997)3. Interbreeding is possible. Combinations of e.g. Burmese Pythons and African Rock Pythons are possible. Pythons reach maturity when they are 5-6 years.
Fascinating as they are, pythons can reach lengths of up to 35 feet. That is also why pythons are exhibited in most Zoological Gardens.
Python snakes are generalist regarding habitats. They thrive in both wet and dry environments. Some pythons are capable of both swimming and climbing in trees which increases the number of available prey to suffocate. The diversified nature of python snakes is what makes pythons such a versatile species.
Adult pythons have a limited number of natural enemies because of their size, and their defensive abilities. However, smaller pythons have many enemies including lizards, crocodiles, large birds, and other large predatory animals.
Large pythons need large animals to satisfy their energy requirements. When the prey has been asphyxiated it is swallowed in full. It takes the python from one to several days to digest a prey, and pythons are generalist regarding prey choice.
Even though most pythons have fairly large teeth, they only use them to hold the prey and to swallow. Python teeth angle backward to keep hold on prey during constriction. Naturally, most prey are swallowed head first as this reduce resistance.
Typically, pythons have high body temperatures, and often, the main challenge for pythons is to keep cool rather than to warm up. Also, the body temperature in pythons is often above air temperature due to the active occupations and search for microhabitats, where the temperature is higher (Shine & Madsen, 1996)4. Most studies on thermoregulation among reptiles have been done on lizards in deserts, where body temperature regulation may be more of an issue than with pythons. In fact, pythons probably don't spend much time thermoregulating at all as a tolerable body temperature may be achievable through thermoconformity, the same as no thermoregulation at all (a complicated word for something very simple that is often used in Zoology).
Dissection of pythons show that the large the snake, the larger the prey in its stomach. The two main explanations are that larger snakes can handle relatively large prey (Shine, 1991)5. There are 4 factors explaining why larger pythons, or snakes in general, eat larger prey items.
Pythons of different sizes forages different places and using different hunting practices and may therefore encounter different prey
Smaller snakes preferably consumes smaller animals as this is the most efficient
Smaller snakes doesn't have the power to overcome large animals
Smaller snakes can not even capture larger prey, simply because they are too slow and weak.
In Florida a population of Burmese Pythons in the Everglades National Park has become a nuisance according to newspapers. According to reports, the ecosystem of Everglades National Park is greatly damaged by the invasion of pythons that have no natural enemies in Florida. The main concern is that the Burmese Python is eradicating populations of endangered animals.
Nobody is quite sure about the size of the python population in Florida, but the highest estimates are in the range of 100000 to 150000. The last reported number with some credibility was 3000.
The population of pythons has grown because of two reasons:
First the hurricane Andrew destroyed some reptile breeding facilities near the Everglades National Park in 1992. About 800 baby pythons were literally blown into the park area. It takes Burmese pythons 5-6 years to mature, and the pythons in Everglades in 2011 is third generation.
Secondly, some pet owners are still disposing their Burmese Pythons into Everglades Nationalpark when they grow too big to handle. Burmese pythons from pet owners breed as well. The very large and heavy species, more than 100 pounds, are probably pythons that used to be pets; wild Burmese Pythons are usually less than 100 pounds.
Although fatalities from snake constriction are rare, visitors to parks and swamps have to be careful when on their own. A picture illustrating the nature of the Burmese python snake is shown below. A 13 foot python snake tried to swallow a 6 foot alligator but ruptured during its venture.
Invasive species such as python snakes in have a detrimental effect on the ecosystem as the native species are not prepared to compete for prey with 20 foot long snakes.
The Ball python is also known as the Royal Python. In some countries the name is translated into the King Python. However, both ball python and royal python are more common names. The reason why Python regius, the Latin name, is called the Ball Python is that it curls into a ball when frightened or scared. The snake is black with golden colored or yellow-brown sides. It can be found in many different colors and varieties, and when kept in captivity, Ball Pythons can reach an age of 40 years.
Reticulated pythons (regal pythons) are popular pets even though they can reach a size where they can be dangerous. They can reach a length of almost 30 foot (9 meters) - and the reticulated python is probably the largest snake species in the world even though the recorded maximum length is only 28.5 foot. This is the only snake known to actually eat people. Most incidences are about snakes killing a person, not swallowing the person also.
This species is said to be able to reach a length of 32 feet. Although not confirmed, African rock pythons can grow huge. They are often exhibited in zoos due to their size. The Afican rock python is widely distributed in Africa. It prefers some degree of humidity. In Africa there are a lot of myths about this snake which is due to its size and the fact that mankind have been aware of its presence ever since man evolved in Africa.
Other and very popular python subspecies include the species listed below. Some names are only used in some areas of the world, so the list below may contain some names foreign to herpetologist in one area while the names are common in other areas of the world:
The black headed python. This species is native of Northern Australia. It is rather small and reaches only a length of 90 inches or approx. 2.25 meters.
Ramsay's python. The Ramsay python is found all over Australia. It reaches a length of 7 feet.
Ringed python. This python is rare and only found in the Bismarck Archipelago (islands north east of New Guinea). They can reach a length of 7 feet.
Calabar python. This was once considered a python but is now recognized as a boa snake.
Children's python. Endemic to Northern Australia. The reason for the name is that children's pythons are very small - only up to 50 inches.
Carpet python. A subspecies of the Diamond Python. It can grow to almost 10 feet.
Amethystine python. One of the largest snakes in the world. It is native of New Guinea and Northern Australia.
Indian python. As the African rock python and the Amethystine Python the Indian Python is one of the world's absolutely largest pythons.
In Florida permits have been issued to allow trained herpetologist to catch python snakes.
Python snakes will not be eradicated by these efforts, but is likely that the population will decrease significantly. If continued efforts are undertaken to remove python snakes from Everglades National Park, and other areas of Florida, the population of pythons can be kept at low levels and the pressure on the ecosystems can be relieved.
Continued efforts may concentrate of a combination of capturing pythons and setting up traps and baits for the pythons.
1 Reed RN. An ecological risk assessment of nonnative boas and pythons as potentially invasive species in the United States. RISK ANALYSIS 25(3) pp. 753-766 (2005)
2 Ayers DY, Shine R. Thermal influences on foraging ability: Body size, posture and cooling rate of an ambush predator, the python Morelia spilota. Functional Ecology 11(3) pp. 342-347 (1997)
3 Shine R, Madsen T. Prey abundance and predator reproduction: Rats and pythons on a tropical Australian floodplain. Ecology 78(4) pp. 1078-1086 (1997)
4 Shine R, Madsen T. Is Thermoregulation Unimportant for Most Reptiles? An example Using Water Pythons Physiological Zoology, Vol. 69(2), pp. 252-269 (2006)
5 Shine R. Why do larger snakes eat larger prey items Functional Ecology, Vol. 5, pp. 493-502 (1991)
Until pythons reaches a certain size they have many natural enemies. Those species preying on python snakes include jackals, hawks, foxes, racoons, mongoose, monitor lizards and eagles. When the pythons grow larger, only big predators such as tigers, alligators, lions, leopards, and jaguars are their enemies.
However, diseases and parasites also take a huge toll on the population of pythons. In Florida, only alligators, parasites and diseases are capable of killing pythons, besides man of course.
Pythons are in fact rather slow animals if moving is about travelling from one place to another. However, it is not very often they have to move very far in a hurry; that means that python do not track prey down. Also, when they have eaten a prey and digested it they often do not have to eat anything again for weeks or months, and don’t have to go hunting for food.
However, as pythons are carnivorous, they need some food from time to time, and must be able to move fast when they are hungry. And they certainly are. The video below how fast a python is when attacking a potential prey. In this case it is an alligator in Florida under attack. Notice how the python first bites the alligator to get a hold on it only to move its body around it to begin squeezing it.
The Indian Python is also known as the Indian Rock Python. It is not only found in India but in Pakistan, Nepal and Sri Lanka. They can grow very large – 20 feet (6-7 meters) and are among the largest snakes in the world. Their close relative, the Burmese python, is known to reach the same lengths but a slightly more heavy-bodied.
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