Definition

1. Noun:
   • A member of the subclass Selachii: A "selachian" is any fish belonging to the subclass Selachii within the class Chondrichthyes. This group is characterized by having a cartilaginous skeleton (not bone), placoid scales (tooth-like scales), and typically five to seven gill slits on each side of the head. The term primarily includes sharks and is sometimes extended to their close relatives like rays and skates.

Usage Examples

• Noun:
  • The great white shark is a well-known selachian.
  • The museum's exhibit features fossils of ancient selachians.
  • Biologists study the unique electroreceptive organs found in many selachians.

Advanced Usage

• In scientific classification: The term "selachian" is used in taxonomic and biological contexts to group and discuss these specific cartilaginous fishes.
  • The research paper compared the fin structures of various selachian species.

Variants and Related Words

• Selachii (n): The scientific subclass name for sharks and sometimes their immediate relatives.
• Elasmobranch (n): A broader taxonomic class (Elasmobranchii) that includes selachians (sharks) along with rays and skates. "Selachian" is often used synonymously with "elasmobranch" in non-technical contexts, though technically "elasmobranch" is the more inclusive term.

Synonyms

• Shark (n): The most common synonym, though "shark" refers specifically to selachians with a fusiform body, while "selachian" can be a broader scientific term.
• Cartilaginous fish (n): A general term for all fish in the class Chondrichthyes, which includes selachians as well as chimaeras (which are not selachians).

Noun

1. any of numerous fishes of the class Chondrichthyes characterized by a cartilaginous skeleton and placoid scales: sharks; rays; skates