Abdomen: in arthropods (crustaceans, insects and arachnids) the abdomen is the hind region of the body, which is usually segmented to a degree (but not visibly in most spiders). In crustacea (e.g. crabs) some of the limbs attach to the abdomen; in insects the limbs are attached to the thorax (the part of the body nearest to the head) and not the abdomen. In vertebrates the abdomen is the part of the body that contains the internal organs (except the heart and lungs).
Palps: in invertebrates, palps are sensory appendages located near the mouth.
Spinnerets: tube-like, movable silk handling structures found at the tip of the abdomen (the hind region of the body) in spiders. There are four pairs of these organs, but in most species there are fewer (usually three). The silk is produced by the silk organs as a liquid, which passes through the spinnerets and is put under tension until the silk becomes a solid thread.