Insects (Insecta) belong to the Phylum Arthropoda, a group of invertebrate animals that includes spiders, crustaceans, scorpions, and centipedes. Like most arthropods, insects have:
- jointed appendages
- exoskeleton
- segmented body
- compound eyes
Insects are a highly successful group of animals. The Class Insecta accounts for more species of animals than any other class of animals. Their numbers are nothing short of remarkable, both in terms of the numbers of individuals as well as the number of species. In fact, there are so many insects that no one knows quite how to count them all. The best that can be done is to make estimates.
Scientists approximate that there may be as many as 30 million species of insects alive today. To date, over one million have been identified. At any one time, the number of individual insects alive on our planet could be in the ballpark of 10 quintillion, which is equivalent to 1018 or 10,000,000,000,000,000,000.
Insects have small body sizes but are otherwise extremely variable in shape and form. In general, the body of an insect is made up of a head, thorax, abdomen, a pair of compound eyes, a pair of antennae, and a set of complex mouthparts (often specialized according to a specific type of feeding).
Classification:
- Kingdom: Animalia
- Phylum: Arthropoda
- Class: Insecta
The Class Insecta contains the following subgroups:- Order: Archaeognatha (bristletails)
- Order: Thysanura (silverfish)
- Order: Ephemeroptera (mayflies)
- Order: Odonata (damselflies and dragonflies)
- Order: Orthoptera (crickets and grasshoppers)
- Order: Plecoptera (stoneflies)
- Order: Grylloblattodea (rock crawlers)
- Order: Phasmotodea (stick and leaf insects)
- Order: Dermaptera (earwigs)
- Order: Mantodea (mantids)
- Order: Blattodea (cockroaches)
- Order: Isoptera (termites)
- Order: Embioptera (web-spinners)
- Order: Zoraptera (angel insects)
- Order: Psocoptera (barklice and booklice)
- Order: Phthiraptera (parasitic lice)
- Order: Hemiptera (bugs)
- Order: Thysanoptera (thrips)
- Order: Megaloptera (dobsonflies and alderflies)
- Order: Rapdhidioptera (snakeflies)
- Order: Neuroptera (antlions and lacewings)
- Order: Coleoptera (beetles)
- Order: Strepsiptera (strepsipterans)
- Order: Mecoptera (scorpionflies)
- Order: Siphonaptera (fleas)
- Order: Diptera (flies)
- Order: Trichoptera (caddisflies)
- Order: Lepidoptera (moths and butterflies)
- Order: Hymenoptera (bees, wasps, ants, sawflies)
Range and Habitat:
The success of insects as a group is reflected by the diversity of habitats they live in, which includes terrestrial (desert, forest, grassland, rainforest), freshwater (ponds, lakes, streams, wetlands) and marine.
References:
- Burnie D, Wilson DE. 2001. Animal. London: Dorling Kindersley. 624 p.
- Myers, P. 2001. Class Insecta, Animal Diversity Web. September 20, 2005
