What is the smallest dolphin species mentioned in the passage?
Blue whale
Hector's dolphin
Orca
What is the main idea of the passage?
Dolphins are the smartest creatures in the ocean.
Dolphins are amazing creatures worth protecting.
Dolphins use echolocation to attack other animals.
How do dolphins communicate with each other?
By echolocating
By using a variety of clicks, whistles, and body language
By making loud noises
What does the word 'sleek' probably mean in the passage?
Slow
Smooth and shiny
Large and heavy