In most spiders the spiracle is just anterior to the spinnerets. Its lateral posterior spinnerets are elongated. They carry the egg sac on the spinnerets on their abdomen. Male tarantulas have special spinnerets surrounding the genital opening. Two glands produce liquid silk and force it through openings in the head called spinnerets. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. In general, synthetic fibers are created by extruding fiber-forming materials through spinnerets, forming a fiber. The posterior, retractable spinnerets are particularly large. They have short spinnerets, located in the rear of the abdomen. Another characteristic are finger-like spinnerets at the end of their abdomen. Most have at least seven or eight spinnerets near the middle of the abdomen. Insects were preserved whole, even delicate wing membranes and spider spinnerets. Silk for the sperm web of the tarantula is exuded from these special spinnerets. Lateral spinnerets are multi-segmented. There are, however, no posterior median spinnerets.