Boa constrictor

Picture from zooplus.de

The boa constrictor, also known as the king snake, king boa or boa, is a species of boas (Boidae) distributed from Colombia to southern South America.

The Boa constrictor is characterized by the great diversity of the appearance of its subspecies. The largest boa constrictor ever recorded was 12 feet long and lived in the Guyana Zoological Park of Georgetown, Guyana. The longest reliably documented skin measures 445 cm without the head and is in the Zoological State Collection in Munich (ZSM 4961/2012). The males remain on average 30 to 40 cm smaller than the females. The coloring of the individual subspecies is just as different as the achievable final size. It ranges from white, red, brown to almost black local forms. Despite this variety in the basic coloration, all boas have dark-edged saddle spots on their backs, the shape of which varies depending on the subspecies. Another distinctive feature of the boa constrictor is its ability to lighten or darken color depending on the temperature. A specimen that is dark in the shade can quickly appear several shades lighter when exposed to sunlight.

The distribution area of the boa constrictor extends from Colombia east of the Andes to Argentina, from sea level to 1,000 meters above sea level. The various subspecies and local forms inhabit the most diverse habitats. However, areas near water bodies with high humidity and dense bushes can be regarded as typical habitats, even if individual populations do occur in semi-deserts.

Picture from zooplus.de

The idol snake is active at dusk and at night. During the day it hides in burrows, hollow trees or other shelters, emerging only occasionally for sunbathing. The juveniles stay mainly in the branches of trees, while adult specimens with increasing age and weight are almost exclusively ground-dwelling. Overall, the idol snake shows little urge to move. A transmitter-equipped adult boa in the wild moved only 135 meters over a 12-day period.

Except for insects and spiders, the idol snake eats all animals that it can handle in terms of size, even small caimans are beaten. However, warm prey is preferred to cold ones. The idol snake generally uses two different hunting methods: either it actively follows the scent trails of the prey or waits as an ambush hunter for the right moment. When the snake is close enough to the prey using either of these methods, it snaps with lightning speed and then crushes the victim with its muscular body loops. The prey is compressed so tightly that a circulatory collapse occurs and death by asphyxiation does not occur, as previously assumed[9]. The Latin species name constrictor ('contractor', 'constrictor') refers to the constricting "choking" by the boa constrictor. Depending on the size of the prey, this process can take up to 16 minutes and represents a considerable effort for the snake. In order not to use up unnecessary energy, the snake feels the heartbeat of the prey and ends the choking process as soon as cardiac arrest has occurred.

A special hunting method was also observed in young boas: They move their tails like a worm and thus actively attract lizards.

Due to a lack of field research, experience from terrarium keeping must be used for reproduction. The corresponding activities – depending on the subspecies – only take place in certain months. During these mating seasons, the female secretes sex attractants that the males actively follow. When the male encounters the female, he scratches the female's flanks with his anal spurs until the latter finally raises his tail and allows penetration of the hemipenis. The advertising can go on for weeks, and there are always a large number of matings that last several hours. The viper gives birth to live young, which are surrounded by a thin skin called the egg membrane or ovule at birth. On average, 120 to 150 days elapse between ovulation and birth, with the time when the young animals are weaned often accompanied by rain. During and after the birth process, the female defends her young, and it has also been observed how females help their young out of the egg shell by bumping with their snouts or encourage them to crawl away. After birth, the young snakes are fully developed and search for food on their own.

The scientific name for the boa snake and thus also for the genus Boa was introduced in 1758 by the Swedish naturalist Carl von Linné in the 10th edition of his Systema Naturae. Various, mostly regionally isolated subspecies are distinguished from the boa snakes. The Central American idol snakes are now considered a separate species (emperor boa (Boa imperator)). Boa imperator and Boa constrictor were separated from each other during the formation of the northern Andes about 3.5 million years ago (allopatric speciation). Both species differ in their cytochrome b genome by 5 to 7%, while the different populations within the two species differ by only 2 to 3%. Other former subspecies of the Boa constrictor, which are now listed as independent species, are the Dominica boa (Boa nebulosa) and the Saint Lucia boa (Boa orophias).

The Dominicaboa is found only on the island of Dominica off the northeast coast of South America. The basic coloring consists of various shades of brown, which darken with age. The drawing hardly stands out from the basic color, only the light borders remain dim. Special features of the Dominicaboa are their extremely slender build and the narrow, flat head. The average height is 180 to 230 cm.

The St. Lucia boa lives on St. Lucia off the north coast of South America. The basic color is yellow-white to light gray with beige-brown saddle spots and numerous black spots. The tail spots are dark red in young animals, but black in adult specimens. The cheeks are often light pink in color. The final size is 240 to 280 cm.

There is a belief among indigenous peoples in the upper Amazon that boa constrictors, such as the anaconda and boa constrictor, impregnate females in the cassava field to sire a brood of snakes. If a woman who has recently given birth dies, it is attributed to such a rape. The Incas equated boa constrictors like the anaconda and idol snake with Amaro, a mythical double-headed serpent feared for its destructive power. In the homeland of the Incas in the high Andes, the idol snake did not occur, but Pachacútec Yupanqui is said to have had giant snakes brought to him as tribute payments by subjugated Indian tribes in the lowlands. The snakes were kept in a snake pit in a prison in Cusco. Criminals and prisoners of war were thrown to them for food; those still alive after three days in the pit are said to have been released. The characteristic drawing of the idol snake can also be found as a motif on numerous pre-Columbian ceramics.

The first immigrants also recognized the practical use of the idol snake. So, the field workers, who came from Africa, kept the snakes in boxes during the day to let them live freely in the house at night to fight the rodents. In Europe and North America, on the other hand, boas were an integral part of migratory animal shacks, with keepers trying to keep them alive with blankets and hot-water bottles. Nowadays, however, the idol snakes are more likely to be found as pets than as livestock in terrariums, with various effects on the natural occurrence. On the other hand, humans also contribute to the development of new habitats for the boa snakes. A now stable boa population has formed on the island of Aruba, which has been proven to have been introduced by humans as an invasive species.