The metasoma is the posterior part of the body, or
tagma, of
arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, o ...
s whose body is composed of three parts, the other two being the
prosoma and the
mesosoma.
In insects, it contains most of the
digestive tract
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...
,
respiratory system, and
circulatory system, and the
apical
Apical means "pertaining to an apex". It may refer to:
*Apical ancestor, refers to the last common ancestor of an entire group, such as a species (biology) or a clan (anthropology)
*Apical (anatomy), an anatomical term of location for features loc ...
segments are typically modified to form
genitalia. In a few of the most primitive insects (the
Archaeognatha), the metasomal segments bear small, articulated appendages called "styli", which are often considered to be
vestigial. There are also pre-apical appendages in most insect orders, called
cerci, which may be multi-segmented and almost resembling a posterior pair of
antennae; these may be variously modified, or lost entirely. Otherwise, most adult insects lack appendages on the metasoma, though many larval insects (e.g.,
caterpillars
Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths).
As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Symph ...
) have some form of appendages, such as
prolegs or, in aquatic insects,
gills.
In
apocrita
Apocrita is a suborder of insects in the order Hymenoptera. It includes wasps, bees, and ants, and consists of many families. It contains the most advanced hymenopterans and is distinguished from Symphyta by the narrow "waist" ( petiole) formed ...
n
Hymenoptera (
wasps,
bee
Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfami ...
s and
ant
Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22,0 ...
s), the metasoma consists of the second
abdominal
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...
segment (which typically forms a
petiole) and those segments posterior to it, and is often called the
gaster rather than referring to it as the "abdomen"; in these insects, the first abdominal segment is called the
propodeum and is fused to the
thorax. The metasoma is
armour
Armour (British English) or armor (American English; see spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, especially direct contact weapons or projectiles during combat, or fr ...
ed with
chitinous plates on the upper surface by the
tergites
A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'ma ...
and on the lower surface by the
sternites
The sternum (pl. "sterna") is the ventral portion of a segment of an arthropod thorax or abdomen.
In insects, the sterna are usually single, large sclerites, and external. However, they can sometimes be divided in two or more, in which case the ...
.
In
scorpions, the metasoma is the tail.
In other chelicerates, such as
spiders, the
mesosoma is fused with the metasoma to form the
opisthosoma
The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma (cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects to ...
.
References
{{reflist
Arthropod anatomy