It is nearly dark. From out of a cave, a black cloud swirls. Suddenly you realize that it is made up of thousands of bats.
Does this make you think of Halloween, or movies about Dracula? People often fear bats as “creatures of the night.” Yet these remarkable animals are helpful to us. They eat insect pests. They pollinate useful plants, as bees do. Their droppings, called guano, are used as fertilizer.
WHAT IS A BAT?
Bats are mammals. They are the only mammals that fly. There are nearly 1,000 species of bats. They are found in all kinds of habitats. Bats live in tropical rain forests. They live in climates so cold that trees won’t grow there. Unlike other mammals, when bats rest they lower their body temperature to save energy. In very cold weather, they hibernate.
A bat’s wings are made of two layers of skin. The wings are supported by bones like those in your hand. The thumbs have claws and lie outside the wings. The bat uses them to cling to the places where it roosts. These may be trees, caves, or even buildings. Muscles attached to the wings power the bat’s flight.
Bats come in many sizes. The largest is the Malayan flying fox. It is 16 inches (41 centimeters) long. Its wings span 5.6 feet (1.7 meters). The Kitti’s hog-nosed bat is the smallest of all mammals. It’s about an inch (3 centimeters) long—the size of a bumblebee—and is also known as the bumblebee bat.
KINDS OF BATS
Bats are divided into two groups, megabats (large) and microbats (small). Megabats are called “flying foxes” because of their foxlike faces. They eat mostly fruit. Because they are sloppy eaters, they spread the seeds and pollen of fruits such as bananas, dates, and figs. This scattering helps the plants reproduce.
Most microbats are meat eaters. About two-thirds of all bat species eat insects. One common American species, the little brown bat, may eat 600 mosquitoes in an hour. Other microbats eat fish, frogs, small birds, lizards, and small mammals.
HOW DO BATS FIND FOOD?
It isn’t true that bats are “blind as a bat.” Most fruit-eating bats feed by day and can see very well. Some even see colors. Even microbats, which sleep by day and hunt by night, have some vision. They use it to find food. They also use smell and, especially, hearing.
Bats send out short pulses of sound. The sounds are usually too high for people to hear. The sound waves spread out in front of the bat. They strike objects in its path and bounce back as an echo. This process, called echolocation, helps the bat find food and avoid bumping into things.
Then there are the famous vampire bats. There are three species of vampire bats, all in Central and South America. And yes, they do feed on blood, mostly that of farm animals. A vampire bat needs about two tablespoons of blood a day.
Even vampire bats have their uses. Their saliva contains a substance that prevents blood from clotting. Doctors use it to make a medicine for heart attack and stroke patients. The name of this medicine is Draculin.
If you swirl something liquid or flowing, or if it swirls, it moves round and round quickly.
whirl, churn, spin, twist
to turn or cause to turn in a twisting spinning fashion
pests are insects or small animals which damage crops or food supplies.
You can describe someone, especially a child, as a pest if they keep bothering you.
a person or thing that annoys, esp by imposing itself when it is not wanted; nuisance
To pollinate a plant or tree means to fertilize it with pollen. This is often done by insects.
to transfer pollen from the anthers to the stigma of (a flower)
to transfer pollen from a stamen to the upper tip of the pistil of (a flower)
A species is a class of plants or animals whose members have the same main characteristics and are able to breed with each other.
kind, sort, type, group
the animals of such a group
The habitat of an animal or plant is the natural environment in which it normally lives or grows.
home, environment, surroundings, element
the environment in which an animal or plant normally lives or grows
Animals that hibernate spend the winter in a state like a deep sleep.
sleep, lie dormant, winter, overwinter
(of some mammals, reptiles, and amphibians) to pass the winter in a dormant condition with metabolism greatly slowed down Compare aestivate
When birds or bats roost somewhere, they rest or sleep there.
A roost is a place where birds or bats rest or sleep.
If bad or wrong things that someone has done in the past have come home to roost, or if their chickens have come home to roost, they are now experiencing the unpleasant effects of these actions.
If you describe someone’s work or activities as sloppy, you mean they have been done in a careless and lazy way.
If you describe someone or something as sloppy, you mean that they are sentimental and romantic.
If a group of people scatter or if you scatter them, they suddenly separate and move in different directions.
If you scatter things over an area, you throw or drop them so that they spread all over the area.
disperse, separate, break up, dispel
saliva is the watery liquid that forms in your mouth and helps you to chew and digest food.
spit, dribble, drool, slaver
the secretion of salivary glands, consisting of a clear usually slightly acid aqueous fluid of variable composition. It moistens the oral cavity, prepares food for swallowing, and initiates the process of digestion
If someone has a stroke, a blood vessel in their brain bursts or becomes blocked, which may kill them or make them unable to move one side of their body.
A stroke of luck or good fortune is something lucky that happens.
A stroke of genius or inspiration is a very good idea that someone suddenly has.