--- title: Crocodiles and alligators — a lesson of Mova's school · trees and pragmatics description: «Crocodiles and alligators», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Crocodiles and alligators are reptiles with four short legs, a long tail and a body that has hardly changed since their ancestors lived alongsid --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/) [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/) / Crocodiles and alligators # Crocodiles and alligators Lesson 29 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/29-crocodiles-and-alligators/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/0/) — Crocodiles and alligators are reptiles with four short legs, a long tail and a body that has hardly changed since their ancestors lived alongside the dinosaurs over 200 million years ago, because it is a perfect shape for hiding in water and ambushing prey. - [1](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/1/) — Their eyes, ears and nostrils sit on top of the head, so a crocodile can lie in a river with only those showing, breathing, watching and listening while the rest of it is hidden like a floating log. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/2/) — To tell them apart, look at the snout and the teeth: an alligator has a wide U-shaped snout and its lower teeth hide when it shuts its mouth, while a crocodile has a narrower V-shaped snout and a big lower tooth still sticks out. - [3](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/3/) — In Peter Pan the crocodile swallows a ticking clock and chases Captain Hook for more; real crocodiles can't chew at all, so they spin over and over in the death roll to twist off chunks and swallow them whole. - [4](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/4/) — And the cute pictures of a capybara sitting on a «crocodile» are usually a caiman in South America, a relative of alligators that has often just eaten and doesn't bother with a big rodent. - [5](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/5/) — Alligators have a wide U-shaped snout and hidden lower teeth, while crocodiles have a narrower V-shaped snout and a lower tooth that shows when the mouth is shut. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/6/) — A saltwater crocodile has one of the strongest bites ever measured, but the muscles that open the jaws are weak, so experts can hold a small one's mouth shut with tape. - [7](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/7/) — A crocodile's eyes, ears and nostrils are on top of its head, and a clear third eyelid protects its eyes under water like goggles. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/9/) — Crocodiles lay eggs in nests; the mother guards them and carries the hatchlings to water in her mouth. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/10/) — The temperature of the nest decides whether the babies will be male or female. - [11](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/11/) — Crocodiles are cold-blooded: they bask in the sun to warm up and gape their mouths to let heat escape, and can go months without eating, because an animal that does not burn food to keep warm uses much less energy. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/12/) — Crocodile ancestors lived alongside dinosaurs over 200 million years ago, and crocodiles are the closest living relatives of birds. - [13](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/13/) — The saltwater crocodile is the largest living reptile, with big males over 6 metres long, and it can travel by sea between islands. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/14/) — In the death roll a crocodile spins in the water to tear chunks off its prey, because it can't chew. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/15/) — American alligators live in swamps, rivers and lakes in the south-eastern USA and recovered from being endangered once hunting was controlled. - [16](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/16/) — Alligators bellow so deeply that the water on their backs dances, and babies call from inside their eggs when ready to hatch. - [17](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/17/) — In the dry season alligators dig gator holes that keep water when everything else dries out, and many other animals drink and live there. - [18](https://md.mova.elamur.ai/free/en/corpora/school/biology/29-crocodiles-and-alligators/18/) — Caimans, South American relatives of alligators, often let capybaras, the world's biggest rodents, rest beside them or on their backs. - ← previous: [Sharks](https://md.mova.elamur.ai/free/en/corpora/school/biology/28-sharks/) - next →: [Snakes and lizards](https://md.mova.elamur.ai/free/en/corpora/school/biology/30-snakes-and-lizards/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)