--- title: Dolphins, porpoises and seals — a lesson of Mova's school · trees and pragmatics description: «Dolphins, porpoises and seals», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: A dolphin is a small toothed whale with one blowhole, about 80 to 100 cone-shaped teeth it never chews with, and a brain that can sleep one --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/) [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/) / Dolphins, porpoises and seals # Dolphins, porpoises and seals Lesson 27 of the biology course of Mova's primary school: 16 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/27-dolphins-porpoises-and-seals/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/0/) — A dolphin is a small toothed whale with one blowhole, about 80 to 100 cone-shaped teeth it never chews with, and a brain that can sleep one half at a time while the other half keeps watch and remembers to breathe. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/2/) — Each bottlenose dolphin has its own signature whistle that works like a name, and friends call each other by copying it, a bit like shouting a mate's name across the playground. - [4](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/4/) — Cartoons show a dolphin always smiling and a seal clapping and balancing a ball; the «smile» is just the shape of a dolphin's mouth, not a happy face, and the clapping seal is a trained sea lion, not what wild seals do. - [5](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/5/) — Dolphins find things by echolocation: they send out fast clicks and listen to the echoes, and sound travels well through water even where it is too muddy to see far. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/6/) — Bottlenose dolphins each have a signature whistle that works like a name, and they remember old friends' whistles for at least 20 years. - [7](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/7/) — Dolphins sleep with half of their brain at a time, switching sides, so they can keep coming up to breathe. - [8](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/8/) — Dolphins ride the waves made by boats and whales, which saves energy and seems to be fun for them. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/9/) — A bottlenose dolphin has around 80 to 100 cone-shaped teeth, gets only one set for life, and swallows fish whole. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/10/) — Some dolphins in Shark Bay, Australia, wear sea sponges on their beaks to protect them while digging for fish, a trick passed mostly from mothers to daughters. - [11](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/11/) — Porpoises are smaller cousins of dolphins with rounded heads, no long beak and spade-shaped teeth. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/12/) — The vaquita, a porpoise in Mexico, is the rarest sea mammal; around ten were reported in recent surveys. - [13](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/13/) — Seals haul out on rocks to rest, warm up and look after pups, and a thick layer of blubber keeps them warm in icy water. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/14/) — Sea lions have small outer ears, can turn their back flippers forward to walk, and swim with their front flippers; true seals have no outer ears and swim with their back flippers. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/15/) — A seal pup alone on a beach is usually waiting for its mother, who may not return if people come close, so stay well away, keep dogs on a lead and call a wildlife rescue only if it looks hurt. - [16](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/16/) — Elephant seals can dive over 1,500 metres deep and stay under for more than an hour, storing oxygen in their blood and muscles and slowing their heart. - [17](https://md.mova.elamur.ai/free/en/corpora/school/biology/27-dolphins-porpoises-and-seals/17/) — Seal whiskers are so sensitive that a blindfolded seal followed a fish's water trail that was more than 30 seconds old. - ← previous: [Whales](https://md.mova.elamur.ai/free/en/corpora/school/biology/26-whales/) - next →: [Sharks](https://md.mova.elamur.ai/free/en/corpora/school/biology/28-sharks/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)