Insect
Say it: IN-sekt
An insect is an arthropod with a body divided into head, thorax and abdomen, three pairs of jointed legs, one pair of antennae and usually wings.
Also: insects, Insecta
Definition
What is an insect?
Insects form the class Insecta, the most species-rich class of animals, with about a million named species and probably several times as many still undescribed. Beetles, flies, ants, bees, butterflies, grasshoppers and cockroaches are all insects. Like other arthropods they wear a jointed exoskeleton made largely of chitin, which they must molt in order to grow.
The insect body has three regions. The head carries the antennae, compound eyes and mouthparts adapted for chewing, sucking or piercing. The thorax bears the three pairs of legs and, in most adults, one or two pairs of wings; insects were the first animals to fly, long before birds or bats. The abdomen holds most of the digestive and reproductive organs. Air enters through small openings called spiracles and travels along branching tubes, the tracheae, directly to the tissues. Many insects change form as they grow, either gradually from nymph to adult or completely, through a larva and a pupa.
Insects pollinate many flowering plants and crops, recycle dead matter and feed countless other animals. Others destroy crops or spread disease: mosquitoes, for example, transmit malaria and dengue. The scientific study of insects is called entomology.
Word parts
Where does the word “insect” come from?
- in-
- intoLatin in
- sect-
- cutLatin secare, to cut (insectum, cut into)
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Terms that go with it
- ArthropodAn arthropod is an invertebrate animal with a segmented body, a hard exoskeleton containing chitin and jointed legs, such as an insect, spider or crab.
- ExoskeletonAn exoskeleton is a hard external skeleton that supports and protects an animal's body, as in insects, spiders and crustaceans.
- MetamorphosisMetamorphosis is a marked change in body form during an animal's development, as when a caterpillar becomes a butterfly or a tadpole a frog.
- ChitinChitin is a tough, nitrogen-containing polysaccharide built from N-acetylglucosamine units that forms arthropod exoskeletons and fungal cell walls.
- PollinationPollination is the delivery of pollen to the female reproductive parts of a seed plant, the step that makes fertilization and seed formation possible.
- VectorIn disease biology, a vector is a living organism, often a bloodsucking insect or tick, that carries a pathogen from one host to another.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- OpenStax Biology 2e, 28.6 Superphylum Ecdysozoa: Arthropods
- NCBI MeSH: Insects
- Truman and Riddiford, The evolution of insect metamorphosis: a developmental and endocrine view (Phil Trans R Soc B, 2019)
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