Gelatin The fillings of both are made by combining ground pork with gelatin cubes, and in the process of cooking, the gelatin melts, creating a soupy interior with a characteristic gelatinous stickiness. Gelatin is used for the clarification of juices, such as apple juice, and of vinegar. Isinglass is obtained from the swim bladders of fish. It is used as a fining agent for wine and beer. Besides hartshorn jelly, from deer antlers (hence the name "hartshorn"), isinglass was one of the oldest sources of gelatin. The consumption of gelatin from particular animals may be forbidden by religious rules or cultural
Swim bladder the blood reaches the heart. Primitive lungs gave an advantage by supplying the heart with oxygenated blood via the cardiac shunt. This theory is robustly supported by the fossil record, the ecology of extant air-breathing fishes, and the physiology of extant fishes. In embryonal development, both lung and swim bladder originate as an outpocketing from the gut; in the case of swim bladders, this connection to the gut continues to exist as the pneumatic duct in the more "primitive" ray-finned fish, and is lost in some of the more derived teleost orders. There are no animals which have both lungs