Insects are a class of living creatures withinthe arthropods that have a chitinous exoskeleton, a three-part body (head, thorax, and abdomen), three pairs of jointed legs, compound eyes, and two antennae. They are among the most diverse groups of animals on the planet, including more than a million described species and representing more than half of all known living organisms. The number of extant species is estimated at between six and ten million.
- Insects typically move about by walking, flying or occasionallyswimming.- Insects are the only invertebrates to have evolved flight.- Many insects spend at least part of their life underwater, withlarval adaptations and some adult insects are aquatic and haveadaptations for swimming.- Some species are capable of walking on the surface of water.- Insects are mostly solitary, but some insects are social and live inlarge, well-organized colonies.- Some insects, like earwigs, show maternal care, guarding theireggs and young.- Insects can communicate with each other in a variety of ways.
The head contains most of the sensing organs, including the•antennae, ocellus and the mouthparts.The torax is a segment that contains the wings and is composed•of three sections. Each segment have one pair of legs.The abdomen is a the last segment of the insect which typically•consists of 11–12 segments.
T he Exoskeleton The exoskeleton is a external rigidcoating composed by chitin used asattachment for muscles and also it’s aprotection from the predators. It coverscompletely the animal and it doesn’tgrown. Infact In the arthropods happensthe molt: the elimination of the oldercoating and the making of a new, largeone.
Metamor phosis Metamorphosis in insects is the biologicalprocess of development all insects mustundergo. There are two forms ofmetamorphosis: incomplete metamorphosisand complete metamorphosis.
• Complete metamorphosis: is where theinsect changes in four stages, an egg,a larva, a pupa, and the adult. In thesespecies, egg hatches to produce a larva,which is generally worm-like in form. Thelarva grows and eventually becomesa pupa, a stage marked by reducedmovement and often sealed withina cocoon. Insects undergo considerablechange in form during the pupal stage,and emerge as adults.
• Incomplete metamorphosis: Insectschange gradually by undergoing a seriesof molts. The molting process begins as theinsects epidermis secretes a new epicuticle.After this new epicuticle is secreted, theepidermis releases a mixture of enzymes thatdigests the endocuticle and thus detaches theold cuticle. When this stage is complete, theinsect makes its body swell by taking in a largequantity of water or air, which makes the oldcuticle split along predefined weaknesseswhere the old exocuticle was thinnest.
Arthropods: Any of numerous invertebrate animals of the phylumArthropoda, including the insects, crustaceans, arachnids, andmyriapods, that are characterized by a chitinous exoskeleton and asegmented body to which jointed appendages are articulated in pairs.Ocellus: A small simple eye, found in many invertebrates, usuallyconsisting of a few sensory cells and a single lens.Chitin: A tough, protective, semitransparent substance, primarily anitrogen-containing polysaccharide, forming the principal componentof arthropod exoskeletons and the cell walls of certain fungi.Cocoon: A protective case of silk or similar fibrous material spun bythe larvae of moths and other insects that serves as a covering fortheir pupal stage.Cuticle: The outermost layer of the skin of vertebrates; epidermis.