First appearance of insects
Insects first appeared around 400 million years ago during the
Devonian period. It is thought that Pterygota first appeared in the
Carboniferous period, 350 million years ago. Then, passing through
the Mesozoic and the Cenozoic periods, many species disappeared and
those that survived eventually reached the present through various
evolutionary processes. Most of the insect colonies distributed in
Korea belong to the Northern Hemisphere biogeographically, similar to
other animals and plants.
As of now, about 12,000 species of insects are
known in Korea. Experts say that Korea has four apparent seasons, and
the insects that appear in each season are different, so as studies on
their distribution continue, a much greater number of insect species
will additionally be identified.
Among these, 900,000 species belong to
Arthropoda, and in the Arthropoda, Insecta account for 850,000
species, which make up at least 80% of the entire animal kingdom.
However, this numerical value only refers to
what has been reported, and as research on actual living insect
species continues, the number is expected to be much greater. Although
opinions about the number of insects living on the Earth differ among
scholars, it is assumed that the number may exceed three to five
million species, and Wilson (1985) predicted that the number of
species could reach five to 30 million. This implies that there are
many more insects to be discovered than have been discovered already.
- The value of such insect diversity is increasing with attempts at realizing the possibility of their utilization as a biological resource with the development of biological engineering and modern technology.
- With their wide distribution, adaptability, and diversity, insects are considered to be the greatest proliferating group of all animals. Although 850,000 insect species have been recorded until now, which accounts for 80% of all animals, experts predict that the number will be much greater when extensive research is accomplished.
Causes of insect proliferation
- Insects have an exoskeleton that protects the body, provides attachment points for muscles, and prevents water evaporation.
- The wings of insects have been a great aid in survival and species dispersal.
- Insects have generally evolved into smaller forms, which allow the use of smaller food resources and lets them hide from predators.
- The development of a tracheal system allows the delivery of external enzymes to muscles where oxidizing occurs, for excellent efficiency.
- Their cold-blooded nature allows survival in unfavorable conditions by minimizing energy usage in freezing temperatures.
- Due to various developments of body structural adaptability,
there are many cases where insects have adapted the same organ to
function in different ways. For example, the front legs of the mantis
are better adapted to catch prey, while those of the mole cricket are
better adapted to dig in the ground. In addition, their respiratory
systems also show this variation and functional adaption, and aquatic
insects are good examples of this.
- Metamorphosis allows completely different niche and food
requirements for larva and imago, so they can adapt and live in
different environments. They have evolved to adapt to unfavorable
conditions by minimizing energy waste by staying dormant in egg,
larva, pupa and imago forms.
Korea Biodiversity Information System > Insect Resource > Insect Classes > Origin of Insects
