Sharks Lesson 28 of the biology course of Mova's primary school: 19 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 .
0 A shark is a fish with no bones at all: its skeleton is cartilage, the bendy stuff in your nose and ears, so it is light and flexible, and because cartilage rots away, shark fossils are mostly teeth. 1 Those teeth sit in rows like a conveyor belt; when one breaks a new one moves forward, so some sharks lose tens of thousands in a lifetime, and that is why a sandy beach can be full of tiny black shark teeth. 2 Sharks have senses you don't: pores on the snout, the ampullae of Lorenzini, feel the faint electricity of a fish's muscles, so a shark can find a fish hiding under the sand. 3 Films like Jaws show sharks hunting people; in truth, sharks kill only a handful of people a year, usually by mistaking a swimmer for a seal, while people kill around 100 million sharks a year. 4 And the biggest shark of all, the whale shark, up to 12 to 18 metres long, eats only plankton and tiny fish and lets snorkellers swim beside it. 5 Sharks lose teeth all the time and grow new ones from the rows behind, some tens of thousands in a lifetime. 6 A shark's skeleton is made of cartilage, which is lighter and bendier than bone, so shark fossils are mostly teeth. 7 Great white sharks often attack seals from below and can burst right out of the water; they grow to about 6 metres and can live over 70 years. 8 Sharks smell blood well, but the story that they can smell one drop from miles away is exaggerated. 9 Sharks don't hunt humans; bites are very rare and often a mistake, and people kill around 100 million sharks a year. 10 The whale shark is the biggest fish in the world, up to about 12 to 18 metres, filters plankton and is harmless to people. 11 Some sharks, like great whites and makos, must keep swimming to push water over their gills, while nurse sharks can rest on the bottom. 12 Sharks have no swim bladder, so many sink if they stop swimming. 13 Sharks sense the faint electricity of living animals with pores on their snouts called the ampullae of Lorenzini. 14 Shark skin is covered in tiny tooth-like scales called dermal denticles that help water flow smoothly, and some swimsuits copy them. 15 Hammerheads have eyes at the ends of a wide flat head, which gives better all-round vision and spreads out their electric sensors. 16 The Greenland shark is the longest-living animal with a backbone known, probably at least 270 years, growing about a centimetre a year. 17 Some sharks and rays lay eggs in leathery cases called mermaid's purses, while other sharks give birth to live pups. 18 Many sharks are endangered because they grow slowly and have few young, and they keep oceans healthy by eating sick fish. ← previous Dolphins, porpoises and sealsnext → Crocodiles and alligators↑ back to Biology This page in Markdown → https://md.mova.elamur.ai/free/en/corpora/school/biology/28-sharks/