Kidney always so simple; in cartilaginous fish and some amphibians, there is also a shorter duct, similar to the amniote ureter, which drains the posterior (metanephric) parts of the kidney, and joins with the archinephric duct at the bladder or cloaca. Indeed, in many cartilaginous fish, the anterior portion of the kidney may degenerate or cease to function altogether in the adult. In the most primitive vertebrates, the hagfish and lampreys, the kidney is unusually simple: it consists of a row of nephrons, each emptying directly into the archinephric duct. Invertebrates may possess excretory organs that are sometimes referred to as
Bladder pipe into the bladder. While the first creation of a double reed pipe with a bladder controlling breath is unknown, it is believed to have originated in Europe before the 13th century. As an intermediate phase between the almost pan-European bagpipe and the Renaissance crumhorn, the Bladder pipe flourished from the 14th to 16th centuries. Examples have been found from Germany, Poland, England, France, Italy, Spain (called the odrecillo) and Estonia (called the rakkopilli). As it declined in popularity, it became associated with beggars and peasants. The early bladder pipe is in a family of the early medieval "chorus" instruments, a