Insects are neumerout invertebrate animals that belong in the Phylum
Arthropoda and Class Insecta. The class Insecta is divided into 2 subclasses:
Apterygota, or wingless insects, and Pterygota, or winged insects. Subclass
Pterygota is futher divided on basis of metamorphosis. Insects that have
undergone incomplete metamorphosis are the Exopterygota. Insects that undergo
complete metamorphosis are the Endopterygota.
Insects have an outer bilateral exoskeleton to which the muscles are attached
to and provides protection for internal organs. The body is divided into 3
main parts which are the head, which include mouthparts, eyes, and antennae;
thorax, which operate the jointed legs and /or wings; and abdomen, which has
organs for digested food, reproducing, and getting rid of waste products.
The major systems in insects are the circulatory, respiratory, nervous,
muscular, digestive, and reproductive systems. In the circulatory system,
blood is pumped by the heart in a tube to the aorta, the head, and to other
organs then enters the ostia openings along the sides of the tube back to the
heart. The respiratory systems carries O2 to cells and takes away CO2 from
cells through branching out to call cells of body. The nervous system consists
of a brain receiving information from eyes, antennae, and controls the whole
body and 2 nerve cords containing ganglia fused together to control activities
of the segment without the help of the brain. insect muscular system is made
up of a
few thousand samll but string muscles allowing the insect to carry objects
heavier than it. The digestive system is basically a long tube where food
enters the mouth to the crop where it is stored, gizzard where it is grinded,
stomach where it is digested, then the undigested parts and wastes are moved
to the intestine, colon then released at the anus. And in the reproductive
system, a new individual is produced sexually when the female eggs produced in
the ovaries united with male sperm produced in the testes.
Both man and insect live almost everywhere, eat all kinds of food, and use
all kinds of materials to build homes so they constantly live in conflict.
Some insects seriously affect man's health and are parasitic on man and other
animals. insects that feed on human or animal blood can carry disease in their
salivary juices and spread the disease to other animals. Many insects irritate
us without disturbing our health. Some bite and sting, and some people are
allergic to them and some insects are injurious to our agricultural crops,
food products, clothing, and wooden buildings. So far man has only partial
success in defending against insects. But some insects species are beneficial
to man. The honey bee, for example, supplies us with honey and the silkworm
supplies us with silk. So bugs really aren't that bad.
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