Surcingle longe lines, requires the use of a surcingle to thread the longe lines through the rings. Compared to a saddle, a surcingle allows more precise adjustment of side reins due to the placement of additional rings. While a saddle only provides one height to attach the rings (the girth buckles), and can be uneven or at the wrong position, a training surcingle places rings at more appropriate locations for ground work. Many surcingle designs allow the side reins to be attached at several different heights along the sides of the horse. When used without a saddle, a surcingle sits just
Animal testing on invertebrates studies on social behavior. General Practical Animal testing on invertebrates Most animal testing involves invertebrates, especially "Drosophila melanogaster", a fruit fly, and "Caenorhabditis elegans", a nematode. These animals offer scientists many advantages over vertebrates, including their short life cycle, simple anatomy and the ease with which large numbers of individuals may be studied. Invertebrates are often cost-effective, as thousands of flies or nematodes can be housed in a single room. With the exception of some cephalopods, invertebrate species are not protected under most animal research legislation, and therefore the total number of invertebrates used remains unknown. Research on invertebrates is