Definition

1. Noun:
   • A primitive eel-shaped vertebrate lacking jaws and paired fins: A jawless fish is a type of aquatic vertebrate characterized by the absence of true jaws and paired appendages (like fins). This group includes living forms such as lampreys and hagfish (cyclostomes), as well as many extinct species.

Usage Examples

• Noun:
  • The lamprey is a well-known example of a jawless fish.
  • Fossils of ancient jawless fish provide clues about early vertebrate evolution.
  • Unlike bony fish, a jawless fish has a simple, cartilaginous skeleton.

Advanced Usage

• In evolutionary biology: The term "jawless fish" is often used to describe the paraphyletic group Agnatha, which represents an early stage in vertebrate development before the evolution of jaws.
  • The study of jawless fish helps scientists understand the transition from invertebrates to vertebrates.

Variants and Related Words

• Agnathan (n): A more formal, scientific synonym for a jawless fish.
  • Agnathans were the dominant vertebrates in early Paleozoic seas.
• Cyclostome (n): A subgroup of living jawless fish, including lampreys and hagfish.
  • Cyclostomes are the only surviving jawless vertebrates.

Synonyms

• Agnathan: A vertebrate of the class Agnatha.
• Lamprey/Hagfish: Specific common names for living types of jawless fish (note: these are specific examples, not perfect synonyms for the entire group).

Related Phrases

• Jawless vertebrate: A phrase often used interchangeably with "jawless fish," particularly in scientific contexts.
  • The earliest jawless vertebrates appeared over 500 million years ago.

Noun

1. eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct forms