Back to TOP of PAGE Q Back to TOP of PAGE R Back to TOP of PAGE S segmentation - In many animals, the body is divided into repeated subunits called segments, such as those in centipedes, insects, and annelids. Segmentation is the state of having or developing a body plan in this way. In many molluscs, the siphon may be used to expel water forcibly, providing a means of propulsion. They are structural components in many sponges, and may serve a protective function in other organisms. In insects and some other terrestrial arthropods, a small opening through which air is taken into the tracheae.
Insects have several spiracles, arranged along the sides of the abdomen.
Back to TOP of PAGE T telson - The last segment of the abdomen in many arthropods. May be flat and paddlelike, buttonlike, or long and spiny, as in the horseshoe crabs. Cnidarians and molluscs are two kinds of orgnaisms which may have tentacles. It is the region where the legs and wings are attached. Lung tissue, vascular tissues, and muscle tissue are all kinds of tissues found in some animals.