Fish Basics
True or false: fish are cold-blooded animals.
True
Bony fish, cartilaginous fish and these jawless fish are the three main groups of fish.
Jawless fish
This fin sits on top of a fish and helps keep it upright in the water.
Dorsal fin
This famous prehistoric shark was much larger than any shark alive today.
Megalodon
Fish use their gills to take in this gas from the water.
Oxygen
These flat, paired body parts are what fish use to swim through the water.
Fins
Sharks, skates and rays all belong to this group of fish, which has no true bone.
Cartilaginous fish
The fin at the back end of a fish that pushes it forward when it swims.
Tail fin (caudal fin)
True or false: sharks can smell a single drop of blood from a long way away in the water.
True
Humans breathe with these organs, which fish do not have.
Lungs
Most fish have these small, overlapping plates covering their bodies for protection.
Scales
Salmon, goldfish and snapper are all examples of this most common group of fish.
Bony fish
This line of sensors along the side of a fish detects vibrations and movement in the water.
Lateral line
These two flat relatives of sharks have wing-like fins and often lie on the sandy bottom.
Skates and rays
Water enters a fish through this body part before flowing over the gills.
Mouth
Because fish have a backbone, scientists group them as this type of animal.
Vertebrates
Lampreys and hagfish are the two main examples of this strange group with no jaws.
Jawless fish
This gas-filled organ helps bony fish control how deep or shallow they sit in the water.
Swim bladder
Sharks are famous for having rows and rows of these, which fall out and are replaced throughout their lives.
Teeth
This bony flap on the side of a bony fish protects and covers the gills.
Operculum
Fish bodies are coated in this slippery substance that helps them slide through the water and protects against disease.
Mucus (slime)
This is the scientific class name for bony fish.
Osteichthyes
A shark's skeleton is made from this flexible material instead of true bone.
Cartilage
Unlike bony fish, sharks have these visible openings on the side of their head instead of a gill cover.
Gill slits
Gills look bright red because they are full of these tiny blood vessels that absorb oxygen.
Capillaries