Ant colonies > Ant body parts

Ant body parts

There can be little doubt that the ants are phylogenetically related, through the lower families of Hymenoptera with the oldest and most primitive of all the existing insects, the Blattoidea, or cockroaches. But while the Blattoid body, as seen, for example, in the common cockroaches, is generalized, that of the ants in its sharp demarcation of the head, thorax and abdomen is highly specialized. These accentuated subdivisions enable anyone to recognize an ant at a glance.

In this respect the ants are the most typical of insects, and may be the ones to which the term insectum were originally applied. While these and many other characters make it seem a far call from the ant to its remote Blattoid ancestors, it must be borne in mind that the individual ant still passes in its embryonic development through a stage in which the body consists of twenty like, or homonomous segments.

Six of these belong morphologically to the head, three to the thorax and the remaining eleven to the abdomen. The first and third segments bear no appendages, the second bears the antennae, the three thoracic segments bear the three pairs of legs, and the second and third of these segments in the males and females develop, at a much later stage, the two pairs of wings.

The first abdominal, which has long been known as the mediary segment, becomes fused with the hind portion of the third thoracic segment during pupal development, as Janet and Emery have demonstrated, and becomes the epinotum of the latter author.

The pedicel consists of the second abdominal segment, or of this and the third segment, while the remaining seven or eight form the gaster.