shark
Sharks are a type of fish with a full cartilaginous skeleton, pectoral fins not fused to the head, and a highly streamlined body. The earliest known sharks date from more than 420 million years ago and are heavily diverse, having a minimum of over 500 species known. They generally only live in saltwater habitats, with very few exceptions that can exist in both fresh and saltwater. They are covered in scales known as…
