Jawless fish are a group of primitive aquatic animals that lack jaws, unlike most other fish. They belong to two main classes: lampreys and hagfish. These creatures have elongated bodies and are often found in both freshwater and marine environments. They feed by suction, using their round mouths to attach to other fish or to scavenge on dead organisms. Jawless fish are considered some of the earliest vertebrates, dating back over 500 million years. Their simple body structure and unique feeding methods provide important insights into the evolution of more complex fish and other vertebrates. They play a crucial role in their ecosystems as both predators and scavengers.