This Presentation will include the origin, evolution, basic biology, ecology, and diversity of fishes having a cartilaginous (non-bony) skeleton. This group includes sharks, rays, chimaeras and other primitive types of fishes, which branched off from the family tree leading to the higher (bony) fishes early in the evolutionary history of Vertebrate animals. Emphasis will be placed on those species that are known to occur in the beachfront and bays that surround Galveston Island, Texas. (Limit 35)