Cartilaginous fish are a group of fish that have skeletons made of cartilage instead of bone. This group includes species like sharks, rays, and skates. Their flexible skeletons allow them to be agile swimmers in various marine environments. These fish typically have a streamlined body, multiple gill slits, and a unique jaw structure. Cartilaginous fish also possess specialized sensory organs that help them detect prey and navigate through the water. They are an important part of the ocean ecosystem, playing roles as both predators and prey.