Abdomen

The abdomen contains the viscera: the stomach, intestine, reproductive organs, and the external genitalia that usually are concerned with mating and egg-laying. In worker bees, the genitalia are incorporated into the mechanism of the sting.

The ten segments of the larval bee's abdomen reduce to nine segments in the adult, as the first abdominal segment joins the thorax to become the hindmost thoracic segment, the propodium.

Honey

Brain

Dorsal Diaphragm

Honey

Dorsal Diaphragm

Brain

Ventral Diaphragm

Figure 5.2. Bee's Internal Anatomy. Lengthwise section through a worker bee.

Ventral Diaphragm

Figure 5.2. Bee's Internal Anatomy. Lengthwise section through a worker bee.

Each abdominal segment contains a large back plate, the tergum, and a smaller ventral plate, the sternum. The successive plates of sequential segments overlap from front to back. The plates connect with each other through inter-segmental membranes. The sides of the segments connect with each other through infolded lateral membranes. Our primitive sequence of joined-rings makes the abdomen distensible and contractile in length as well as allows the tip of the abdomen to bend up and down. Long retractor muscles that course along the length of the abdomen pull the segments together to shorten the abdomen. Shorter protractor muscles in each segment oppose the retractor muscles to lengthen the abdomen. Compressor muscles within each segment draw the ter-gum and sternum of each segment closer together. A short tubular stalk, the petiole (think of a wasp's waist), unites the abdomen to the thorax permitting much movement between the two. The nerve cord, alimentary canal and dorsal vessel traverse the petiole, again as in a conduit.

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