Sleep and hibernation Lesson 55 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 .
0 Every animal needs rest, but they rest in amazing ways: dolphins sleep with half their brain, giraffes nap standing up, bats sleep upside down, and koalas sleep most of the day. 1 Hibernation is something much bigger than a long nap: the body cools down, the heart slows from racing to crawling, and the animal lives on its stored fat through the hungry time of winter. 2 Picture a hedgehog curled under a pile of leaves in November; its heart drops from about 190 beats a minute to around 20, and it stays almost switched off until spring, which is why bonfire piles must be checked before lighting. 3 Some animals sleep through summer instead: the African lungfish digs into drying mud, wraps itself in slime and waits for the rain, and that is called aestivation. 4 Cartoons show bears snoring all winter and waking up in spring with a big stretch, and goldfish forgetting everything in 3 seconds; real bears sleep more lightly than hedgehogs, and goldfish remember for months. 5 Hedgehogs hibernate from about November to March, when there are few beetles, worms or slugs to eat; the heartbeat drops from about 190 to around 20 beats a minute, and they may wake and move nests a few times. 6 Bears sleep through winter in dens living on their fat; their temperature drops only a little, mothers give birth in the den and make milk for the cubs from their stored fat, a bear wakes up thin and hungry in spring, and it can go months without eating, drinking or going to the toilet. 7 The hazel dormouse can hibernate for six months or more, after fattening up on hazelnuts and berries in autumn. 8 Dolphins sleep with half their brain at a time and one eye open, so they can still come up to breathe and watch for danger. 9 Giraffes sleep very little, in short naps, mostly standing, because getting up takes a long time with lions around; koalas sleep about 18 to 22 hours a day, because their gum leaves give little energy. 10 Bats sleep hanging upside down with their foot tendons locked, and in cold countries they hibernate in caves and attics; bats are not blind. 11 Common frogs spend winter in mud or under logs, and some males rest at the bottom of ponds, taking in oxygen through their skin. 12 The North American wood frog can freeze solid in winter, with its heart stopped, and thaw and hop away in spring. 14 Children of 9 to 10 need about 9 to 12 hours of sleep a night; during sleep the body grows and repairs itself, and the brain sorts memories; bright light from a screen before bed tells the brain it is still daytime, so sleep comes harder. 15 Fish have no eyelids, but many rest by slowing down and floating still; some parrotfish sleep in a bubble of slime. 16 Mediterranean tortoises hibernate, and owners guided by a vet keep them steady at about 5 degrees so they neither wake early nor freeze. 17 Waking up from hibernation burns a lot of stored fat that has to last the winter, and there is no food to replace it, so hibernating hedgehogs, bats and tortoises must be left alone. 18 African lungfish survive the dry season sealed in slime in dried mud, breathing air, sometimes for years; this summer sleep is aestivation. ← previous Migration: the great journeysnext → How plants grow: seeds, light, water and air↑ back to Biology This page in Markdown → https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/