Gaster

This article is about the anatomical use of the word Gaster. For information on the surname Gaster, see Gaster (surname). For information on the medicine, see famotidine.

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.

The gaster is the bulbous posterior portion of the metasoma found in Apocrita Hymenoptera (bees, wasps and ants). This begins with abdominal segment III on most ants, but some make a postpetiole out of segment III, in which case the gaster begins with abdominal segment IV.[1][2]