Paddlefish (family Polyodontidae) are primitive Chondrostean ray-finned fishes. The paddlefish can be distinguished by its large mouth and its elongated, spatula-like snout, called a rostrum, which is longer than the rest of the head. These fish are not closely related to sharks, which are in a different taxonomic class, but they do have some body parts that resemble those of sharks such as their skeletons, primarily composed of cartilage, and their deeply forked heterocercal tail fins. This type of fish's age is hard to determine but many scientists[who?] think that they live 50 years or more. There are only two modern species of these fish: the Chinese paddlefish (Psephurus gladius) and the American paddlefish (Polyodon spathula). Both have declined greatly in abundance, and the Chinese species may now be extinct. In some areas, paddlefish are referred to as "Spoonbill", "Spoonies" or "Spoonbill Catfish". The American species is Missouri's State Aquatic Animal.