Under a relatively low magnification of 45x, this 2006 scanning electron micrograph (SEM) depicted a dorsal, or superior view, of a male louse, Pediculus humanus var. corporis. The head, or cephalic region is at the left, from which its two antennae were extended. The head was attached to the thoracic region, which gave rise to its three pairs of jointed legs. While the abdominal region, towards the far right, is the region in which was housed the stomach, and intestines. The 'jointed' nature of its extremities, designates this organism as a member of the phylum Arthropoda, and the fact that there are three pairs of legs, the louse is, thereby, placed into the class, Insecta. Note the small, 'hair-like' structures adorning the exoskeletal surface of this insect. These are known as 'setae', and are not hairs at all, but extensions of the chitinous exoskeletal surface, which provide the organism with sensorial data about its surroundings.
CDC/ Joseph Strycharz, Ph.D.; Kyong Sup Yoon, Ph.D.; Frank Collins, Ph.D.
November 2, 2012