|Description:||Under a low magnification of 43X, almost 4X greater than PHIL 10125, this scanning electron microscopic (SEM) image depicted a rather ominous scene, for entangled in this brown recluse spider web was the exoskeletal remains of an unidentified insect, which was believed to be an ant. Known as “spider silk”, the strands of silk are produced by the spider’s “spinnerets”, which are glands located in the distal tip of its abdomen. Once the prey has become entangled in the web, the spider will cautiously, though aggressively, approach the prey, subduing it with a neurotoxic bite, which also contains proteolytic, or protein-destroying enzymes, and further enwraps the prey in a web cocoon like the one seen here. In this particular view you’ll note one of the victim’s compound eyes, adjacent to which was the proximal end of one of its two antennae.|
The compound eye is given this name due to the fact that the single large eye is really made up of many repeating units known as "ommatidia”. Each ommatidium is composed of separate units made up of a photoreceptor cell, support cell, and pigment cells. Though each of these visual mechanisms functions as a separate organ, together they provide the organism with a "compound” picture of its environment. Due to what is referred to as the "flicker effect”, the compound eye is made very sensitive to movement, with each ommatidium turning on and off, as objects pass across its field of view. The bilateral anatomical placement of the insect's eyes provides the organism with a very wide range of visual sensitivity.
The antenna is composed of three main regions: scape, pedicle, and flagellum. The scape attaches the sensory organ to the head region, and the pedicle joins the distal, jointed flagellum to the scape.