Question

Select the set of fishes which belong to the class Osteichthyes :

• A. Saw fish, Fighting fish and Dog fish
• B. Devil fish, Cuttlefish and Hagfish
• C. Flying fish, Angel fish and Fighting fish
• D. Starfish, Hagfish and Cuttlefish

Hint:

Logic Tip: Beware of "fake" fishes! Starfish (Echinoderm), Jellyfish (Cnidarian), Cuttlefish (Mollusc), and Devil fish (Mollusc) are all invertebrates. Seeing any of these immediately disqualifies the option!

Answer 1

The Correct Option is C

Concept:
The phylum Chordata includes the subphylum Vertebrata, which is further divided into classes of fishes. The two major classes are Chondrichthyes (cartilaginous fishes like sharks and rays) and Osteichthyes (bony fishes). Additionally, many aquatic animals with "fish" in their name are actually invertebrates.
Step 1:

• Saw fish (Pristis): Belongs to Chondrichthyes (cartilaginous).
• Fighting fish (Betta): Belongs to Osteichthyes.
• Dog fish (Scoliodon): Belongs to Chondrichthyes (a type of shark). Because it contains cartilaginous fishes, this set is incorrect.
Step 2:

• Devil fish (Octopus): Belongs to phylum Mollusca (invertebrate).
• Cuttlefish (Sepia): Belongs to phylum Mollusca (invertebrate).
• Hagfish (Myxine): Belongs to class Cyclostomata (jawless vertebrate). None of these are bony fishes. This set is completely incorrect.
Step 3:

• Starfish (Asterias): Belongs to phylum Echinodermata (invertebrate).
• Hagfish (Myxine): Class Cyclostomata.
• Cuttlefish (Sepia): Phylum Mollusca. Again, none of these belong to Osteichthyes. This set is incorrect.
Step 4:

• Flying fish (Exocoetus): A marine bony fish.
• Angel fish (Pterophyllum): A freshwater/marine aquarium bony fish.
• Fighting fish (Betta): A freshwater aquarium bony fish. All three animals in this group possess a bony endoskeleton and belong to the class Osteichthyes.
Step 5:
Therefore, the set containing exclusively members of class Osteichthyes is Option (3).