Which animal is a fish?

Which animal is a fish?

• A. Jellyfish
• B. Goldfish
• C. Whales
• D. Rattlesnakes

Answer: (B)

Being a fish means an aquatic vertebrate that uses gills to breathe underwater, has fins for swimming, and is usually covered with scales. The goldfish fits all of these traits: it lives in water, breathes through gills, has fins to move, and has scales on its body. The others don’t match that combination: whales are mammals that breathe air with lungs; jellyfish are invertebrates without a backbone or gills; rattlesnakes are reptiles with dry, scaly skin and lungs. So the goldfish is the one that is a fish.

Being a fish means an aquatic vertebrate that uses gills to breathe underwater, has fins for swimming, and is usually covered with scales. The goldfish fits all of these traits: it lives in water, breathes through gills, has fins to move, and has scales on its body. The others don’t match that combination: whales are mammals that breathe air with lungs; jellyfish are invertebrates without a backbone or gills; rattlesnakes are reptiles with dry, scaly skin and lungs. So the goldfish is the one that is a fish.