The prothorax is the foremost of the three segments in the
thorax
The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen.
In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...
of an
insect
Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
, and bears the first pair of
legs. Its principal
sclerites (exoskeletal plates) are the pronotum (
dorsal
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
The fus ...
), the prosternum (
ventral), and the propleuron (
lateral
Lateral is a geometric term of location which may also refer to:
Biology and healthcare
* Lateral (anatomy), a term of location meaning "towards the side"
* Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx
* Lateral release ( ...
) on each side. The prothorax never bears wings in extant insects (except in some cases of
atavism), though some fossil groups possessed wing-like projections.
All adult insects possess legs on the prothorax, though in a few groups (e.g., the
butterfly
Butterflies are winged insects from the lepidopteran superfamily Papilionoidea, characterized by large, often brightly coloured wings that often fold together when at rest, and a conspicuous, fluttering flight. The oldest butterfly fossi ...
family
Nymphalidae
The Nymphalidae are the largest family of butterflies, with more than 6,000 species distributed throughout most of the world. Belonging to the superfamily Papilionoidea, they are usually medium-sized to large butterflies. Most species ha ...
) the forelegs are greatly reduced. In many groups of insects, the pronotum is reduced in size, but in a few it is hypertrophied, such as in all
beetle
Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
s (
Coleoptera). In most
treehoppers (family
Membracidae, order
Hemiptera
Hemiptera (; ) is an order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from ...
), the pronotum is expanded into often fantastic shapes that enhance their
camouflage
Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
or
mimicry
In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. In the simples ...
. Similarly, in the
Tetrigidae, the pronotum is extended backward to cover the flight wings, supplanting the function of the
tegmina.
See also
*
Glossary of entomology terms
This glossary of entomology describes terms used in the formal study of insect species by entomology, entomologists.
A–C
A synthetic chlorinated hydrocarbon insecticide, toxic to vertebr ...
*
Insect morphology
Insect morphology is the study and description of the morphology (biology), physical form of insects. The terminology used to describe insects is similar to that used for other arthropods due to their shared evolutionary history. Three physical f ...
*
Mesothorax
*
Metathorax
*
Thorax (insect anatomy)
References
Insect anatomy
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