Pack animal Pack animal A pack animal or beast of burden is an individual or type of working animal used by humans as means of transporting materials by attaching them so their weight bears on the animal's back, in contrast to draft animals which pull loads but do not carry them. Traditional pack animals are diverse including camels, goats, yaks, reindeer, water buffaloes, and llamas as well as the more familiar pack animals like horses, donkeys and mules. The term "pack animal" is traditionally used in contrast to "draft animal", which is a working animal that typically pulls a load behind itself
Animal testing on invertebrates 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 the foundation for current understanding of