Biology:Gaster (insect anatomy)

Short description: Bulbous posterior portion of the metasoma

In the worker ant the metasoma is divided into the narrow petiole and bulbous gaster. The abdomen technically includes the metasoma and the propodeum which is fused to the thorax. No Entomologists uses these terms, but the internet community seems to

The gaster is the bulbous posterior portion of the metasoma found in hymenopterans of the suborder Apocrita (bees, wasps and ants). This begins with abdominal segment III on most ants, but some make a constricted postpetiole out of segment III, in which case the gaster begins with abdominal segment IV.

Certain ants in the genus Cataglyphis, including Cataglyphis bicolor and Cataglyphis fortis, have a cubiform petiole that allows them to decrease their inertia (and therefore increase their speed) by raising their gaster into an upright position.

• Cataglyphis nigra with raised gaster

References

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