Urinary bladder an organ that regularly stores a hyperosmotic concentration of urine. It therefore is relatively impermeable and has multiple epithelial layers. The urinary bladder of the cetaceans (whales and dolphins) is proportionally smaller than that of land-dwelling mammals. In the whole class of Aves there is no urinary bladder per se. Although all birds have kidneys, the ureters open directly into a cloaca which serves as a reservoir for urine, fecal matter, and eggs. In crustaceans, the urinary bladder consists of two sets of lateral and central lobes. Urinary bladder The urinary bladder is a hollow muscular organ in humans and
Pig bladder Mob football, Medieval football, and La soule.) For centuries before the invention of the paint tube, artists used to store their paints in pig bladders. When the artist was ready to use the paint, they would puncture a hole in the bladder and squeeze out the desired amount of paint. They would have to mend the hole when finished and the whole process was quite messy. The oil paint tube was invented in 1841, as the primary packaging of paints for transport and storage. In the bian lian ("face changing") style of Chinese opera, painted pig bladders were used as