Final answer:
Elasmobranchs, including sharks, rays, and skates, are the subgroup of cartilaginous fishes that are strong swimmers, have keen senses, and are considered expert predators due to their advanced sensory systems and specialized skeletal features.
Step-by-step explanation:
Elasmobranchs, which include sharks, rays, and skates, are renowned for their swimming abilities, keen sensory systems, and predatory efficiency. They belong to the subclass of cartilaginous fishes, characterized by a skeleton made primarily of cartilage rather than bone. Elasmobranchs lack swim bladders, which are found in most bony fishes, and thus they maintain buoyancy by using their large, muscular fins to push against the water. Their complex brains enable problem-solving and social interaction. Moreover, they are equipped with keen senses — such as a highly developed sense of smell and the ability to detect electrical fields — making them formidable predators of the sea.
There are distinct characteristics that set elasmobranchs apart from other fish, such as their jaw structure, which allows them to be effective at capturing and consuming a wide range of prey. They also possess multiple gill slits, and their skin is typically rough with tiny tooth-like structures called denticles that reduce drag while swimming.