Vertebrate Class Identification

Vertebrates are animals possessing a backbone or vertebral column. They belong to the phylum Chordata, subphylum Vertebrata. Invertebrates lack a backbone.

Analyzing Classification Options

Let's examine each option to determine if it represents a vertebrate class:

• Cyclostomata: This group includes jawless fish (like lampreys and hagfish). They are considered primitive vertebrates.
• Annelida: This is a phylum of invertebrate animals known as segmented worms (like earthworms and leeches). They do NOT possess a backbone.
• Pisces: This term traditionally encompasses all classes of fish (jawed and jawless), which are vertebrates. Modern classification often splits this into multiple classes (Chondrichthyes, Osteichthyes, etc.), but all are vertebrates.
• Reptilia: This is a class within Vertebrata, including animals like snakes, lizards, turtles, and crocodiles. They are characterized by having a backbone.

Conclusion on Vertebrate Classes

Based on the analysis, Annelida is the only option listed that is an invertebrate phylum, not a vertebrate class.