Insects are a class of arthropods that have three body segments, three pairs of legs, and two antennae. They display two types of metamorphosis - complete metamorphosis with four life stages (egg, larva, pupa, adult), or incomplete metamorphosis with gradual changes through molting. Insects are highly diverse and make up over half of all known living organisms, with over a million described species.

1. The Insects

2. Insects are a class of living creatures within
the 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.

3. - Insects typically move about by walking, flying or occasionally
swimming.
- Insects are the only invertebrates to have evolved flight.
- Many insects spend at least part of their life underwater, with
larval adaptations and some adult insects are aquatic and have
adaptations for swimming.
- Some species are capable of walking on the surface of water.
- Insects are mostly solitary, but some insects are social and live in
large, well-organized colonies.
- Some insects, like earwigs, show maternal care, guarding their
eggs and young.
- Insects can communicate with each other in a variety of ways.

4. The head contains most of the sensing organs, including the
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antennae, ocellus and the mouthparts.
The torax is a segment that contains the wings and is composed
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of three sections. Each segment have one pair of legs.
The abdomen is a the last segment of the insect which typically
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consists of 11–12 segments.

5. T he Exoskeleton
The exoskeleton is a external rigid
coating composed by chitin used as
attachment for muscles and also it’s a
protection from the predators. It covers
completely the animal and it doesn’t
grown. Infact In the arthropods happens
the molt: the elimination of the older
coating and the making of a new, large
one.

6. Metamor phosis
Metamorphosis in insects is the biological
process of development all insects must
undergo. There are two forms of
metamorphosis: incomplete metamorphosis
and complete metamorphosis.

7. •
Complete metamorphosis: is where the
insect changes in four stages, an egg,
a larva, a pupa, and the adult. In these
species, egg hatches to produce a larva,
which is generally worm-like in form. The
larva grows and eventually becomes
a pupa, a stage marked by reduced
movement and often sealed within
a cocoon. Insects undergo considerable
change in form during the pupal stage,
and emerge as adults.

8. •
Incomplete metamorphosis: Insects
change gradually by undergoing a series
of molts. The molting process begins as the
insect's epidermis secretes a new epicuticle.
After this new epicuticle is secreted, the
epidermis releases a mixture of enzymes that
digests the endocuticle and thus detaches the
old cuticle. When this stage is complete, the
insect makes its body swell by taking in a large
quantity of water or air, which makes the old
cuticle split along predefined weaknesses
where the old exocuticle was thinnest.

9. Arthropods: Any of numerous invertebrate animals of the phylum
Arthropoda, including the insects, crustaceans, arachnids, and
myriapods, that are characterized by a chitinous exoskeleton and a
segmented body to which jointed appendages are articulated in pairs.
Ocellus: A small simple eye, found in many invertebrates, usually
consisting of a few sensory cells and a single lens.
Chitin: A tough, protective, semitransparent substance, primarily a
nitrogen-containing polysaccharide, forming the principal component
of arthropod exoskeletons and the cell walls of certain fungi.
Cocoon: A protective case of silk or similar fibrous material spun by
the larvae of moths and other insects that serves as a covering for
their pupal stage.
Cuticle: The outermost layer of the skin of vertebrates; epidermis.