The boa constrictor (scientific name also ''Boa constrictor''), also known as the common boa, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of large, non-venomous, heavy-bodied

snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more j ...

that is frequently kept and bred in captivity. The boa constrictor is a member of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Boidae The Boidae, commonly known as boas or boids, are a family of nonvenomous snakes primarily found in the Americas, as well as Africa, Europe, Asia, and some Pacific Islands. Boas include some of the world's largest snakes, with the green anacond ...

. The species is native to tropical

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

. A staple of private collections and public displays, its color pattern is highly variable yet distinctive. Four subspecies are recognized.

Common names

Though all

boid The Boidae, commonly known as boas or boids, are a family of nonvenomous snakes primarily found in the Americas, as well as Africa, Europe, Asia, and some Pacific Islands. Boas include some of the world's largest snakes, with the green anaconda ...

s are indeed constrictors, only ''Boa constrictor'' (and its subspecies) is commonly referred to, in

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...

, as a boa constrictor—an example of a species being referred to colloquially using its scientific binomial name. The species and subspecies of ''B. constrictor'' are part of a variable, diverse group of

New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. ...

boids referred to as "red-tailed" boas, comprising the species ''Boa constrictor'' and ''

Boa imperator ''Boa imperator'' or ''Boa constrictor imperator'' (in common usage) is a large, heavy-bodied, nonvenomous species of snake, of the boa genus, that is commonly kept in captivity. ''Boa imperator'' is part of the family Boidae and is found in Mex ...

''. Within the exotic pet trade, it is known as a "BCC"—an abbreviation of its scientific name—to distinguish it from other boa species, such as ''

'' (known as "BCI" or "boa constrictor imperator"). Other regional names include the ''chij-chan'' (

Mayan Mayan most commonly refers to: * Maya peoples, various indigenous peoples of Mesoamerica and northern Central America * Maya civilization, pre-Columbian culture of Mesoamerica and northern Central America * Mayan languages, language family spoken ...

), ''jiboia'' (

Portuguese Portuguese may refer to: * anything of, from, or related to the country and nation of Portugal ** Portuguese cuisine, traditional foods ** Portuguese language, a Romance language *** Portuguese dialects, variants of the Portuguese language ** Portu ...

), and ''macajuel'' (

Trinidadian Trinidadians and Tobagonians, colloquially known as Trinis or Trinbagonians, are the people who are identified with the country of Trinidad and Tobago. The country is home to people of many different national, ethnic and religious origins. As a ...

Subspecies

Several subspecies of ''Boa constrictor'' have been described in the past, but many of these are poorly differentiated, and further research may redefine many of them. Some appear to be based more on location rather than on biological differences. ''

'', ''

Boa nebulosa ''Boa nebulosa'', the Dominican boa constrictor, is a species of snake in the family Boidae. The species is endemic to Dominica Dominica ( or ; Kalinago: ; french: Dominique; Dominican Creole French: ), officially the Commonwealth of Domini ...

'', ''

Boa orophias ''Boa orophias'', the San Lucia boa, is a species of snake in the family Boidae. The species is endemic to Saint Lucia. ''Boa orophias'' was described as a full species by Carl Linnaeus in 1758, but many later authors have classified it as a subspe ...

'' and ''Boa sigma'' have all been elevated to full species status. Several other subspecies have been described at different times, but currently, these are no longer considered to be valid subspecies by many herpetologists and taxonomists. They include: * ''B. c. amarali'' Olive Griffith Stull, Stull, 1932 * ''B. c. melanogaster'' species:James K. Langhammer, Langhammer, 1983: a ''nomen dubium''

Description

Size and weight

The boa constrictor is a large snake, although it is only modestly sized in comparison to other large snakes, such as the reticulated python, Burmese python, or the occasionally Sympatry, sympatric green anaconda, and can reach lengths from depending on the locality and the availability of suitable prey.Maurice, B. ''International Wildlife Encyclopedia'' Third Edition. Clear sexual dimorphism is seen in the species, with females generally being larger in both length and girth than males. The usual size of mature female boas is between whereas males are between .species:Chris Mattison, Mattison, C. (2007). ''The New Encyclopedia of Snakes''. Princeton University Press. . Females commonly exceed , particularly in captivity, where lengths up to or even can be seen.Wagner, D. "Boas". Barron's. The largest documented non-stretched dry skin is deposited at ''Bavarian State Collection of Zoology, Zoologische Staatssammlung München'' (ZSM 4961/2012) and measures 14.6 ft (4.45 m) without head. A report of a boa constrictor growing up to was later found to be a misidentified green anaconda.species:John C. Murphy, Murphy JC, species:Robert W. Henderson, Henderson RW (1997). ''Tales of Giant Snakes: A Historical Natural History of Anacondas and Pythons''. Malabar, Florida: Krieger Publishing Co. . The boa constrictor is a heavy-bodied snake, and large specimens can weigh up to . Females, the larger sex, more commonly weigh . Some specimens of this species can reach or possibly exceed , although this is not usual. The size and weight of a boa constrictor depends on subspecies, locale, and the availability of suitable prey. ''B. c. constrictor'' reaches, and occasionally tops, the averages given above, as it is one of the relatively large subspecies of ''Boa constrictor''. Other examples of sexual dimorphism in the species include males generally having longer tails to contain the Hemipenis, hemipenes and also longer pelvic spurs, which are used to grip and stimulate the female during copulation.Mark O'Shea (herpetologist), O'Shea M (2007). ''Boas and Pythons of the World''. Princeton, New Jersey: Princeton University Press. . Pelvic spurs are the only external sign of the rudimentary hind legs and pelvis and are seen in all boas and pythons.

Coloring

The coloring of boa constrictors can vary greatly depending on the locality. However, they are generally a brown, gray, or cream base color, patterned with brown or reddish-brown "saddles" that become more pronounced towards the tail. This coloring gives ''B. constrictor'' subspecies the common name of "red-tailed boas." The coloring works as a very effective camouflage in the jungles and forests of its natural range. Some individuals exhibit pigmentary disorders, such as albinism. Although these individuals are rare in the wild, they are common in captivity, where they are often selectively bred to make a variety of different color "morphs". Boa constrictors have an arrow-shaped head with very distinctive stripes on it: One runs dorsally from the snout to the back of the head; the others run from the snout to the eyes and then from the eyes to the jaw. BoaConstrictor

Boa constrictors can Infrared sensing in snakes, sense heat via cells in their lips, though they lack the labial pits surrounding these receptors seen in many members of the family Boidae. Boa constrictors also have two lungs, a smaller (non-functional) left and an enlarged (functional) right lung to better fit their elongated shape, unlike many Colubridae, colubrid snakes, which have completely lost the left lung.

Distribution and habitat

Depending on the subspecies, ''Boa constrictor'' can be found through South America north of 35°S (Colombia, Ecuador, Peru, Venezuela, Trinidad and Tobago, Guyana, Suriname, French Guiana, Brazil, Bolivia, Uruguay, and Argentina), and many other islands along the coasts of South America. Introduced populations exist in Cozumel, extreme southern Florida, and St. Croix in the U.S. Virgin Islands. The Type locality (biology), type locality given is "Indiis"—a mistake, according to Peters and Orejas-Miranda (1970).:fr:Roy Wallace McDiarmid, McDiarmid RW, Jonathan A. Campbell, Campbell JA, species:T'Shaka A. Touré, Touré TA (1999). ''Snake Species of the World: A Taxonomic and Geographic Reference Volume 1''. Washington, District of Columbia: Herpetologists' League. (series). (volume). ''B. constrictor'' flourishes in a wide variety of environmental conditions, from tropical rainforests to arid semidesert country.Stidworthy J (1974). ''Snakes of the World''. New York: Grosset & Dunlap Inc. . However, it prefers to live in rainforest due to the humidity and temperature, natural cover from predators, and vast amount of potential prey. It is commonly found in or along rivers and streams, as it is a very capable swimmer. Boa constrictors also occupy the burrows of medium-sized mammals, where they can hide from potential predators.

Behavior

Boa constrictors generally live on their own and do not interact with any other snakes unless they want to mate. They are nocturnal, but they may bask during the day when night-time temperatures are too low. As Arboreal locomotion, semi-arboreal snakes, young boa constrictors may climb into trees and shrubs to forage; however, they become mostly Terrestrial animal#Terrestrial Classes, terrestrial as they become older and heavier.species:John M. Mehrtens, Mehrtens JM (1987). ''Living Snakes of the World in Color.'' New York: Sterling Publishers. . Boa constrictors strike when they perceive a threat. Their bite can be painful, especially from large snakes, but is rarely dangerous to humans. Specimens from Central America are more irascible, hissing loudly and striking repeatedly when disturbed, while those from South America tame down more readily. Like all snakes, boa constrictors in a Moulting#Reptiles, shed cycle are more unpredictable, because the substance that lubricates between the old skin and the new makes their eyes appear milky, blue, or opaque so that the snake cannot see very well, causing it to be more defensive than it might otherwise be.

Hunting and diet

Their prey includes a wide variety of small to medium-sized mammals and birds. The bulk of their diet consists of rodents (such as squirrels, mice, rats and agoutis), but larger lizards (such as ameivas, iguanas and tegus) and mammals as big as New World monkey, monkeys, marsupials, armadillos, Peccary, wild pigs and ocelots are also reported to have been consumed. Domestic animals such as dogs, cats and rabbits are frequently consumed. Young boa constrictors eat small Mouse, mice, birds, bats, lizards, and amphibians. The size of the prey item increases as they get older and larger. Once a boa constrictor has caught its prey, it will wrap its coils around the animal and constrict it until it Asphyxia, suffocates. The boa's powerful muscles allow it to exert a great deal of pressure, and the prey is typically killed within a few minutes. Boa constrictors are ambush predators, so they often lie in wait for an appropriate prey to come along, then they attack a moment before the prey can escape. However, they have also been known to actively hunt, particularly in regions with a low concentration of suitable prey, and this behavior generally occurs at night. The boa first strikes at the prey, grabbing it with its teeth; it then proceeds to constrict the prey until death before consuming it whole. Unconsciousness and death likely result from shutting off vital Hemodynamics, blood flow to the heart and brain, rather than suffocation as was previously believed; constriction can interfere with blood flow and overwhelm the prey's usual blood pressure and Circulatory system, circulation. This would lead to unconsciousness and death very quickly. Their teeth also help force the animal down the throat while muscles then move it toward the stomach. It takes the snake about 4–6 days to fully digest the food, depending on the size of the prey and the local temperature. After this, the snake may not eat for a week to several months, due to its slow metabolism.

Reproduction and development

Central fusion and terminal fusion automixis

Boa constrictors are Viviparity, viviparous, giving birth to live young. They generally breed in the dry season—between April and August—and are Polygyny in animals, polygynous; thus, males may mate with multiple females. Half of all females breed in a given year, and a larger percentage of males actively attempt to locate a mate. Due to their polygynous nature, many of these males will be unsuccessful. As such, female boas in inadequate physical condition are unlikely to attempt to mate, or to produce viable young if they do mate. Reproduction in boas is almost exclusively sexual. In 2010, a boa constrictor was shown to have reproduced asexually via parthenogenesis. The Epicrates maurus, Colombian rainbow boa (''Epicrates maurus'') was found to reproduce by facultative parthenogenesis resulting in production of WW female progeny. The WW females were likely produced by terminal Parthenogenesis#Automictic, automixis (see Figure), a type of parthenogenesis in which two terminal haploid products of meiosis fuse to form a zygote, which then develops into a daughter progeny. This is only the third genetically confirmed case of consecutive virgin births of viable offspring from a single female within any vertebrate lineage. In 2017, boa constrictors, along with ''

s'' and Burmese pythons, were found to contain a new set of sex determining chromosomes. Males were discovered to contain a pair of XY sex determining chromosomes, while females have a XX pair. This is the first time snakes were thought to contain male Heterogametic sex, heterogamety; since then it has been found in ball pythons (''Python regius'') as well. During the breeding season, the female boa constrictor emits pheromones from her cloaca to attract males, which may then wrestle to select one to breed with her. During breeding, the male curls his tail around the female's and the hemipenes (or male reproductive organs) are inserted. Copulation can last from a few minutes to several hours and may occur several times over a period of a few weeks. After this period, ovulation may not occur immediately, but the female can hold the sperm inside her for up to one year. When the female ovulates, a midbody swell can be noticed that appears similar to the snake having eaten a large meal. The female then sheds two to three weeks after ovulation, in what is known as a post-ovulation shed which lasts another 2–3 weeks, which is longer than a normal shed. The gestation period, which is counted from the postovulation shed, is around 100–120 days. The female then gives birth to young that average in length. The Litter (animal), litter size varies between females but can be between 10 and 65 young, with an average of 25, although some of the young may be stillborn or unfertilized eggs known as "slugs". The young are independent at birth and grow rapidly for the first few years, shedding regularly (once every one to two months). At 3–4 years, boa constrictors become sexually mature and reach the adult size of , although they continue to grow at a slow rate for the rest of their lives.Smith, Charles R. (1999)
Boa constrictor (''Boa constrictor'')
Siar Anthranir Reptiles At this point, they shed less frequently, about every 2–4 months.species:Peter J. Stafford, Stafford, P. (1986). ''Pythons and Boas''. Neptune, New Jersey: T.F.H. Publications. .

Captivity

This species does well in Captivity (animal), captivity, usually becoming quite tame. It is a common sight in both zoos and private reptile collections. Though still exported from their native South America in significant numbers, they are widely bred in captivity. When kept in captivity, they are fed mice, rats, rabbits, chickens, and chicks depending on the size and age of the individual. Captive life expectancy is 20 to 30 years, with rare accounts of over 40 years, making them a long-term commitment as a pet. The greatest reliable age recorded for a boa constrictor in captivity is 40 years, 3 months, and 14 days. This boa constrictor was named Popeye and died in the Philadelphia Zoo, Pennsylvania, on April 15, 1977. Proper animal husbandry is the most significant factor in captive lifespan; this includes providing adequate space, correct temperatures and humidity, and suitable food items. Up to 41.5% of captive boas test positive for Inclusion body disease, eosinophilic inclusion bodies.

Economic significance

Boa constrictors are very popular within the exotic pet trade and have been both captured in the wild and bred in captivity. Today, most captive boa constrictors are captive-bred, but between 1977 and 1983, 113,000 live boa constrictors were imported into the United States. These huge numbers of wild-caught snakes have put considerable pressure on some wild populations. Boa constrictors have also been hunted for their meat and skins, and are a common sight at markets within their geographic range. After the reticulated python, boa constrictors are the snake most commonly killed for snakeskin products, such as shoes, bags, and other items of clothing. In some areas, they have an important role in regulating the opossum populations, preventing the potential transmission of leishmaniasis to humans.Pough, F. Harvey (2004). ''Herpetology'' (third edition). . In other areas, they are often let loose within the communities to control the rodent populations.

Conservation

All boa constrictors fall under CITES and are listed under CITES Appendix II, except ''B. c. occidentalis'', which is listed in CITES Appendix I. In some regions, boa constrictor numbers have been severely hit by predation from humans and other animals and over-collection for the exotic pet and snakeskin trades. Most populations, though, are not under threat of immediate extinction; thus, they are within Appendix II rather than Appendix I. Boa constrictors may be an invasive species in Florida and Aruba.