The boa constrictor is the only animal everyone calls by its Latin name
Every boid snake constricts its prey, yet only one species gets called a boa constrictor in everyday English, which happens to be its formal scientific name too. No other animal is routinely referred to by its binomial. It is also one of the few snakes caught reproducing without a father.
Native to tropical South America, from Colombia and Venezuela south to Argentina, the common boa has also been introduced to Cozumel, the tip of Florida and St. Croix. Pet keepers call it a BCC to separate it from its close relative Boa imperator, and locals know it as jiboia in Portuguese or chij-chan in Mayan. Its brown, grey or cream body carries darker saddles that turn reddish towards the tail, earning the group the name red-tailed boas. Captive breeders exploit rare colour disorders such as albinism to create a range of morphs.
It is big but not enormous next to pythons or anacondas, ranging from about 0.9 to 4 metres. Females outgrow males, typically reaching 2.1 to 3 metres, and heavy individuals weigh up to 27 kg. A reported 5.6 metre boa turned out to be a misidentified green anaconda. Small spurs near the vent are the last outward trace of hind legs, and inside, the left lung has shrunk to a useless stub while the right does the breathing.
Boas are mostly nocturnal ambush hunters, though they will go looking when prey is scarce. Young ones climb; heavier adults stay on the ground. After seizing prey they coil around it, and current thinking is that death comes from cutting off blood flow to the heart and brain rather than from suffocation, as was once believed. Digestion takes four to six days, and a slow metabolism means the snake may then fast for weeks or months. Central American boas tend to be touchier than South American ones, and any boa about to shed sees poorly and gets defensive.
Females give birth to live young, usually 10 to 65 per litter with 25 typical, and can store sperm for up to a year. In 2010 one was shown to have reproduced by parthenogenesis, and in 2017 researchers found that males carry XY sex chromosomes, the first evidence of that system in snakes.
Source: Boa constrictor
