What are insects? Sometimes people might take the misconception that spider is a kind of eight-leg-insect. If you think so, it's t ime for you to learn more! Now, let's take a look at the classification of insects.
In the field of biological classification , insects are grouped under Class Insecta, phylum Arthropoda, which is the largest phylum in Kingdom Animalia. In phylum Arthropoda, insects are the unique group that are winged and capable to fly.
Let's study to the word "insect". The word "insect" came from the Latin insectum , the prefix " in" means "above" and " sectum" has the denotation of "to cut in". Integrating those meanings then "insect" means many segments.
Adult insects have a segmented body, divided into a head, thorax and abdomen. They also have the following characteristics: a head with a pair of antennae, a pair of compound eyes, 0-3 ocelli, and mouthparts; thorax with 3 pairs of legs, wingless or usually two pairs of wings; a genital opening at the end of abdomen. Besides, the insect has a tracheal system for respiration, and a main excretory organ called Malpighian tubules.
Spiders, for instance, have eight legs and their body is divided into two parts: the cephalothorax and the abdomen. These characteristics are quite different from that of insects, so spiders are not insects. Spiders are also the members of Arthropoda but belong to class Arachnida, which makes them relatives of insects.