Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa (now synonymous for Animalia) and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between taxa. Humans make use of many animal species, such as for food (including meat, milk, and eggs), for materials (such as leather and wool), as pets, and as working animals including for transport. Dogs have been used in hunting, as have birds of prey, while many terrestrial and aquatic animals were hunted for sports. Nonhuman animals have appeared in art from the earliest times and are featured in mythology and religion. Etymology
The word "animal" comes from the Latin animalis, meaning having breath, having soul or living being. The biological definition includes all members of the kingdom Animalia. In colloquial usage, the term animal is often used to refer only to nonhuman animals. The term "metazoa" is from  Ancient Greek μετα (meta, used to mean "later") and ζῷᾰ (zōia, plural of ζῷον zōion "animal"). Characteristics
Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and multicellular. Unlike plants and algae, which produce their own nutrients, animals are heterotrophic, feeding on organic material and digesting it internally. With very few exceptions, animals respire aerobically.
Erythema annulare centrifugum (EAC), is a descriptive term for a class of skin lesion presenting redness (erythema) in a ring form (anulare) that spreads from a center (centrifugum). It was first described by Darier in 1916. Many different terms have been used to classify these types of lesions and it is still controversial on what exactly defines EAC. Some of the types include annular erythema (deep and superficial), erythema perstans, erythema gyratum perstans, erythema gyratum repens, darier erythema (deep gyrate erythema) and erythema figuratum perstans. Symptoms
Occurring at any age these lesions appear as raised pink-red ring or bulls-eye marks. They range in size from 0.5–8 cm (0.20–3.15 in). The lesions sometimes increase size and spread over time and may not be complete rings but irregular shapes. Distribution is usually on the thighs and legs but can also appear on the upper extremities, areas not exposed to sunlight, trunk or face. Currently EAC is not known to be contagious, but as many cases are incorrectly diagnosed as EAC, it is difficult to be certain. Causes
Often no specific cause for the eruptions is found. However, it is sometimes linked to underlying diseases and conditions such as:

Food (including blue cheese or tomatoes). Contact Dermatitis (i.e. cleaning agents, fabric softeners, etc.) Fungal, Bacterial and Viral infections such as sinusitis, tuberculosis, candidiasis or tinea. Drugs including finasteride, etizolam (and benzodiazepines), chloroquine, hydroxychloroquine, oestrogen, penicillin and amitriptyline. Cancer (especially the type known as erythema gyratum perstans, in which there are concentric and whirling rings). Primary biliary cirrhosis. Graves disease. Appendicitis.