Amazing Animals: Fish Quiz

Other animals that live in water, such as frogs in the tadpole stage, also have gills and backbones, but fish are the only backboned animals with two-chambered hearts.

The study of fish is called ichthyology, from the Greek words for "fish" and "discourse."

As fish age, their scales grow larger in size.

The cells of the lateral line are connected to a nerve, deep in the body, that leads to the acoustico-lateralis area of the brain. In some fish, the gas bladder serves as a resonator that aids in hearing.

The largest fish is the whale shark, which is estimated to reach a length of 60 feet (18 meters) or more.

The sailfish is the fastest fish in the ocean, cruising at speeds of up to 68 mph (109 kph).

Probably the most remarkable of all fish migrations is that of the European eel, which travels about 3,000 miles (4,828 kilometers) to spawn in the Sargasso Sea in the North Atlantic Ocean. These eels accomplish the journey in about three years.

Sharks, skates and rays belong to the chondrichthyes class of fish. These fish have no bones; their skeletons are made of cartilage.

Robotic singing fish, such as Big Mouth Billy Bass, were popular gag gifts in recent years.

Flying fish can glide in the air as far as 20 feet (6 meters) or more if there's a tailwind.