Are bats blind? Is the bat a bird or a mammal? Which bird is dangerous? What are mammals? How does a spider spin its web? What is a boat-bug? Read on to find the answers.
 

Which bird is considered dangerous?

The Cassowary is a bird to watch out for, as it is known to get furious and can attack and kill even a human being! It somewhat resembles an Ostrich and is found in Australia and New Guinea. Like the Ostrich, it too cannot fly, but can run at a fairly good speed. 

The Cassowary has a bony head, and its body is covered with coarse feathers. Like its appearance, the behaviour of the Cassowary is also coarse, and this bird actually throws temper tantrums! It can jump up and down in the air when angry, and it kicks furiously at trees for no apparent reason. The Cassowary has two feet. Each foot has 3 toes; the inner foot has a long straight claw, which can be used to slash a person's stomach!

Cassowaries are generally found in groups, and are often seen by the waterside, as they feed on fish. 
 

What are mammals?

Mammals are those animals that have a backbone or vertebra. They have a hairy body and are warm-blooded creatures. Unlike non-mammals, mammals do not lay eggs. They give birth to their young, and have mammary glands. Man is also a part of the mammal family.

Some mammals live on land, while some live in water. Some are carnivorous while others are herbivores. The cow, chimpanzee, kangaroo, pig, camel, rabbit, squirrel, wolf, lion and cheetah are all mammals. Waterborne mammals include the whale and the dolphin. There are over 4000 distinct species of mammals.
 

Why is the bat not a bird but a mammal?

Though the bat flies, it is not considered a bird as it has mammary glands and suckles its young.
 

The bat is a formidable creature to look at: very dreary and almost black in colour. It is generally a night bird, and 'see' at night with the help of sonar (sound pulses), which enables them to sense their surroundings. The expression 'blind as a bat' is incorrect, as bats do have eyesight. 

Whilst resting, the bat has a peculiar way of hanging upside down from the branches of trees. Bats emit a high sound, similar to a shriek.  

Some bats, called the vampire bats, feed on the blood of animals and birds, even of humans! Their teeth can be very sharp. The largest bat is known as the Flying Fox. It has a body length of over 40 cm (almost one and a half ft)! Bats normally have a life span of around 20 years.
 

What's so special about the spider's web?

The spider is a creature that is found practically in all parts of the world. Spiders secrete a certain liquid from their abdominal glands, that comes out in the form of a fine thread. It is this 'thread' that a spider uses to spin a web. The thread is normally sticky, so as to trap insects. The webs may be wheel-shaped or funnel-shaped.

Spiders are particularly prevalent in England and Wales.  According to estimates, in one year, spiders eat as many insects as make up the entire population of the U.K! A lot of food for a little spider! 
 

Which insect swims upside down?

The back-swimmer, also known as the boat bug, is one insect that swims upside down in the water, with the help of their hind legs. These boat bugs are tiny in size and mostly live in the water. They can stay beneath it for nearly six hours because there is space for air between their body and wings. There are almost 200 species of back-swimmers. These can be found in all parts of the world, and are considered dangerous to both man and beast.