The clarinet could easily be mistaken for an oboe, except for the mouthpiece, which uses a single reed. Clarinets come in a number of different sizes, and the standard B-flat clarinet is just over 2 feet long. Some musical works require the clarinetist to play several types of clarinet in the same piece. The 2 to 4 clarinets in the orchestra play both melodies and harmonies, and they have a dark rich sound in their lower notes, while the upper part of the clarinet's range is bright and resonant. You play the clarinet as you do an oboe, by holding it upright, blowing through the reed, and using your hands to change the pitches by opening and closing the keys with your fingers.
The smaller E-flat clarinet is just like a standard clarinet, but about half the length. Its shorter size allows it to play higher notes.
This is the grandfather of the clarinet family. The bass clarinet is so large that its top and bottom are bent to make it easier for musicians to hold and play. Its greater length allows it to play some of the lowest notes in the orchestra.