Insects, General Applicable Terms

(There are estimated to be 10,000 million insects living in each square kilometer of habitable land on earth or 26,000 million per square mile)

abdomen
The region of the body of an arthropod behind the thorax, in insects comprising up to ten segments.
adaptive radiation, radiation adaptive
The invasion, through time, of a wide diversity of adaptive zones and niches by a group of organisms undergoing evolutionary diversification.
aerial
A reference to activities which take place in flight; that is, in the air.
air sac
The thin-walled expansion of the tracheal system of an arthropod, which increases or strengthens the inspiration and the exhalation of air.

Air sacs also give buoyancy to aquatic insects, and in dragonflies, it provides insulation around the thoracic wing muscles.

alimentary
1. Of or relating to nourishment or nutrition.
2. Furnishing sustenance or maintenance.
alimentary canal
1. The gut or digestive system in an insect.
2. A tube adapted for digestion, through which food passes.

It is a complex organ, consisting of the mouth cavity, pharynx, esophagus, stomach, and the small and large intestines.

altruism
Apparently a self-sacrificing behavior performed by one creature for the benefit of others.
ametabolous
A reference to insects having no metamorphosis (no major change in physical form); that is, the Apterygota (being wingless), in which larvae hatch from eggs in a form essentially identical to the adult except for the size and undeveloped genitalia which develop and the size increases at each molting or periodically shedding of part or all of the outer covering of their bodies (hair, skin, or feathers, etc.) which is then replaced with a new growth.
amino acid
One of about twenty compounds comprising both a basic amino group and an acidic carboxyl group (organic compound with acidic properties), which combine in their hundreds to form proteins.
amphibious
A reference to the capability of living in water and on land.
anaerobic
Pertaining to organisms; such as, many bacteria, that are able to live in an environment that lacks free oxygen.
annelid
1. A type of worm characterized by numerous appendage-bearing or leg-bearing body segments.
2. An invertebrate organism with a flat body that is divided into segments.

Earthworms and leeches are annelids of the Phylum Anelida.

apodeme
An ingrowth or other rigid process of the exoskeleton, typically used for muscle attachment.
appendage
Any limb or articulated outgrowth of the insect body; such as, the antennae or wings.
Arachnid
A member of the class Arachnida (spiders, scorpions, ticks, and mites) of the phylum Chelicerata.