Definition

1. Noun:
   • A primitive aquatic vertebrate: A cyclostome is a type of jawless vertebrate that lives in water. This group includes lampreys and hagfishes, which are among the most ancient living vertebrates.

Examples of Usage

• Noun:
  • The lamprey is a well-known example of a cyclostome.
  • Cyclostomes have a simple, cartilaginous skeleton and a round, sucking mouth.

Advanced Usage

• In scientific classification: The term "cyclostome" is often used in evolutionary biology and zoology to refer to the group Cyclostomata, which is considered the sister group to all jawed vertebrates (gnathostomes).
  • The study of cyclostomes provides key insights into early vertebrate evolution.

Variants and Related Words

• Cyclostomata (n): The taxonomic class or superclass that includes all cyclostomes.
  • Cyclostomata is divided into two orders: Petromyzontiformes (lampreys) and Myxiniformes (hagfishes).

Synonyms

• Jawless fish: A common descriptive synonym, though "cyclostome" is the more precise taxonomic term.
• Agnathan: A broader, less common scientific term for jawless vertebrates, which includes extinct groups alongside cyclostomes.

Related Phrases

• Cyclostome morphology: Refers to the physical form and structure of these animals.
  • The research paper focused on cyclostome morphology.

Noun

1. primitive aquatic vertebrate