Bats are the only flying mammals. Their wings are made of leathery skin.
Most types of bat sleep during the day, hanging upside down in caves, attics acid other dark places. They come out at night to hunt.
Bats find things in the dark by giving out a series of high-pitched clicks — the bats tell where they are and locate (find) prey from the echoes (sounds that bounce back to them). This is called echo location.
Bats are not blind — their eyesight is as good as that of most humans.
There are 900 species of bat, living on all continents except Antarctica.
Most bats feed on insects, but fruit bats reed on fruit.
Many tropical flowers rely on fruit bats to spread their pollen.
Frog-eating bats can tell edible frogs from poisonous ones by the frogs’ 0iating calls.
The vampire bats of tropical Latin America feed on blood, sucking it from animals such as cattle and horses. A colony of 100 vampire bats can feed from the blood of 25 cows or 14,000 chickens in one night.
False vampire bats are bats that do not suck on blood, but feed on other smalI creatures such as bats and rats. The greater false vampire bat of Southeast Asia is one of the biggest of all bats.
There are about 130 species of fruit bat known as flying foxes. They fly on leathery wings, which can span as much as 1.8 m, to feed on fruits such as bananas and figs.
Salmon are river and sea fish caught or farmed in huge quantities for food.
All salmon are born in rivers and lakes far inland, then swim down river and out to sea.
Adult salmon spend anything from 6 months to 7 years in the oceans, before returning to rivers and swimming upstream to spawn (lay their eggs).
More than five salmon species, including the sockeye and the chinook, spawn in North American rivers running into the North Pacific.
Cherry salmon spawn in eastern Asian rivers, and amago salmon spawn in Japanese rivers.
Atlantic salmon spawn in rivers in northern Europe and eastern Canada.
Spawning salmon return to the same stream they were born in, up to 3,000 km inland. They are probably sensitive to the chemical and mineral make-up of streams and rivers, helping them to recognize their own stream.
To reach their spawning grounds, salmon have to swim upstream against strong currents, often leaping as high as 5 m to clear waterfalls.
When salmon reach their spawning grounds, they mate. The female lays up to 20,000 eggs.
After spawning, the weakened salmon head down river again, but few make it as far as the sea.
Salmon returning to their spawning ground make mighty leaps up raging ion cats. The journey can take months.
Annuals are plants that grow from seed, flower, disperse their seeds and die in a single season.
Some annuals’ seeds lie dormant in the ground before conditions are right for germination.
With an annual, producing flowers, fruits and seeds exhausts the plant’s food reserves, so once the seeds are dispersed the green parts of the plant die.
Many crops are annuals, including peas and beans, squashes, and cereals such as maize and wheat.
Annual flowers include petunias, lobelias, buttercups and delphiniums.
Biennials live for two years.
In the first year the young plant grows a ring of leaves and builds up an underground food store such as a bulb or taproot like beetroots and carrots. The food store sustains the plant through the winter.
In the second year the plant sends up a stem in spring. It flowers in summer.
Many vegetables are biennials, including beetroot, carrots and turnips.
Biennial flowers include wallflowers, carnations, sweet williams and evening primroses.
Dinosaurs were reptiles that dominated life on land from about 220 million to 65 million years ago, when all of them mysteriously became extinct.
Although modern reptiles walk with bent legs splayed out, dinosaurs had straight legs under their bodies – this meant they could run fast or grow heavy.
Some dinosaurs ran on their back two legs, as birds do. Others had four sturdy legs like an elephant’s.
Dinosaurs are split into two groups according to their hipbones – saurischians had reptile-like hips and ornithischians had bird-like hips.
Saurischians were either swift, two-legged predators called theropods, or hefty four-legged herbivores called sauropods.
Theropods had acute eyesight, fearsome claws and sharp teeth. They included Tyrannosaurus rex, one of the biggest hunting animals to ever live on land – over 15 m long, 5 m tall and weighing more than 7 tonnes.
Sauropods had massive bodies, long tails, and long, snake-like necks.
The sauropod Brachiosaurus was over 23 m long, weighed 80 tonnes and towered 12 m into the air. It was one of the biggest creatures ever to live on land.
Most dinosaurs are known from fossilized bones, but fossilized eggs, footprints and droppings have also been found. In 1913, mummified hadrosaur skin was found.
Some scientists think the dinosaurs died out after a huge meteor struck Earth off Mexico, creating a cloud that blocked the sun’s light and heat.