Agnatha are a group of jawless fish, distinguished by their lack of jaws and paired fins, features that set them apart from most other vertebrates. These creatures have elongated, eel-like bodies and rely on simple, circular mouths—often equipped with rows of teeth made from keratin—for feeding. Their cartilaginous skeletons provide flexibility, and many possess specialized structures such as rasping tongues or suction discs for attachment and feeding. As some of the most primitive vertebrates, agnathans offer valuable insights into early vertebrate evolution.
- Agnatha means "without jaws," referring to their jawless condition.
- They have simple, circular mouths instead of hinged jaws.
- Their bodies are elongated and eel-like.
- Agnathans possess cartilaginous (not bony) skeletons.
- They are considered some of the most primitive vertebrates.
- Modern representatives include lampreys and hagfish.
- Fossil evidence shows they were more diverse in the past.
- They lack paired fins, a feature common in jawed vertebrates.
Agnatha means 'jawless.'
Lampreys and hagfish are modern agnathans.
Agnatha lack jaws and paired fins, have cartilaginous skeletons, and elongated bodies.
Agnatha are significant because they represent an ancient, jawless lineage, providing insight into early vertebrate evolution.
Modern agnathans are vital for understanding vertebrate origins, but fossil agnathans also highlight a once diverse and widespread group, bridging the gap between invertebrates and vertebrates.