Are all lizards poisonous?
Lizards are disliked by everyone because they always look
ugly and frightening. They climb on the walls and can even walk on the ceilings
upside down without falling.
But these small common
lizards are not the only ones living on our earth. There are more than 2500
different kinds of lizards but only two are actually poisonous. These are
found in the American deserts, and in Mexico.
Lizards are cold-blooded reptiles like snakes. But unlike
snakes, the bodies of lizards are divided into three parts: head, trunk and
tail. Most species of lizards have four legs, but some have no legs at all and
look more like snakes.
Many species of lizards have an unusual capacity of discarding
their tails. This often helps them escape an enemy if it catches hold of
their tail. Later, the lizard grows a new tail!
Lizards are hardy creatures and can adapt themselves to almost any surroundings. The lizards that live among grass or trees are coloured, but those living in the desert are dull grey or brown. Some kinds of lizards can change their colour to hide in their surroundings.
Most lizards are hatched from eggs. The smaller ones eat
insects, but a few larger ones eat birds and small animals. Lizards like to live
in warm climates. To escape the cold, they hibernate or sleep during cold winters
and again become active in summer.
The lizards we commonly see are small in size, about 7-8
centimetres long, but the bigger ones found in some countries can be as large
as 3 meters long.
Read also: Unknow story of some rare birds in the world
Are spiders harmful and poisonous?
The ability to spin webs gives spiders a special place
amongst animals. Its silk, used for many different purposes, is produced in the
form of liquid. Manufactured in some of the abdominal glands, it comes out
through many tiny holes from the spinning organs at the tip of its abdomen.
Spider silk is strong and elastic. The finest single fibre is
about one –millionth of an inch in diameter! Different types of spiders make
many different types of webs which are more or less characteristic of spider
families: sheet webs, funnel webs, tube webs, reticular webs, etc. These webs
are traps to catch and hold insects which are the food for spiders.
The poison glands in spiders are controlled by them and are
used in some special ways. Those who use their web to catch their prey do not
use this poison, but those who catch insects by grasping them with their fangs,
kill their prey with poison.
Very few spiders are dangerously poisonous to man. The majority of them are no more dangerous than wasps or hornets. A few species of spiders,
however, produce poisons that can cause severe pain and illness. The black widow spider of America, the
tarantulas and banana spiders are notorious, but death due to their bite is
very rare.
All spiders use their poison in self-defence. Only when they
are trapped and feel that escape is impossible they use their poison.
The life span of spiders is usually short. The wolf spiders
of northern America may live several years, but the spiders of the temperate
zone usually live only one year.