--- title: Big snakes: pythons, boas and anacondas, and how big they really get — a lesson of Mova's school · trees and pragmatics description: «Big snakes: pythons, boas and anacondas, and how big they really get», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Pythons, boas and anacondas are the giants of the snake world. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/) / Big snakes: pythons, boas and anaconda… # Big snakes: pythons, boas and anacondas, and how big they really get Lesson 321 of the biology course of Mova's primary school: 18 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/0/) — Pythons, boas and anacondas are the giants of the snake world. - [1](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/1/) — They have no venom; they hunt by grabbing prey and wrapping it in their coils, which is why they are called constrictors. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/2/) — The longest snake is the reticulated python of Southeast Asia, and the heaviest is the green anaconda of South America. - [4](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/4/) — Stories always make big snakes bigger. - [5](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/5/) — Old posters show 15-metre monsters swallowing canoes, but a reward for a living snake over about 9 metres was reportedly never claimed, and a snake held close to a camera looks far bigger than it is. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/6/) — Their bodies are full of surprises: a few hundred backbones, two tiny spurs left over from the legs of their lizard ancestors, jaws that stretch around an egg wider than the head, and a heart that grows after a big meal. - [7](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/7/) — Think of a python in a museum skeleton: it looks like a long zip with a rib on each side of every tooth. - [8](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/8/) — The reticulated python of Southeast Asia is the longest snake; the longest reliably measured ones were about 7 metres, though stories claim far more. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/9/) — The green anaconda of South America is the heaviest snake; a big female can weigh well over 100 kilograms, and females are much bigger than males. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/10/) — Anacondas live mostly in swamps and slow rivers, where the water helps hold up their heavy bodies. - [11](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/11/) — No snake anywhere near 15 metres long has ever been measured; a reward offered over a hundred years ago for a living snake longer than about 9 metres was reportedly never claimed. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/12/) — Constrictors coil around prey and tighten each time it breathes out; scientists found the squeeze mainly stops the blood flowing, so the prey faints within moments rather than being crushed. - [13](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/13/) — A big python has a few hundred backbones, often around 300 or more, and nearly every one carries a pair of ribs; you have 33 backbones. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/14/) — Boas and pythons have two small spurs near the tail, the last tiny bits of back legs from the lizards with legs that snakes evolved from. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/15/) — The two halves of a snake's lower jaw are joined by stretchy tissue and the jaw bones are loosely joined to the skull; snakes do not «unhinge» their jaws, and they swallow prey whole, usually head first. - [16](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/16/) — A big python can live for months, sometimes over a year, after one large meal, because a cold-blooded animal burns very little energy; its heart and gut grow bigger for a few days to digest the meal. - [17](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/17/) — Burmese pythons let go or escaped from people's homes now live wild in the Everglades of Florida, where they have eaten huge numbers of small mammals and birds; the biggest caught there was reported at about 5.5 metres. - [18](https://md.mova.elamur.ai/free/en/corpora/school/biology/321-big-snakes-pythons-boas-and-anacondas-and-how-big-they-really-get/18/) — Female pythons coil around their eggs to guard them, and a Burmese python mother can twitch her muscles to keep them several degrees warmer than the air; boas and anacondas give birth to live babies. - ← previous: [Bears up close: noses, claws, dens, the honey myth and bear safety](https://md.mova.elamur.ai/free/en/corpora/school/biology/320-bears-up-close-noses-claws-dens-the-honey-myth-and-bear-safety/) - next →: [Snakes to keep away from: cobras, mambas, vipers and rattlesnakes](https://md.mova.elamur.ai/free/en/corpora/school/biology/322-snakes-to-keep-away-from-cobras-mambas-vipers-and-rattlesnakes/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)