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No, it is a brass instument created by the "composer" John Philip Sousa who wrote most of America's popular marching band music. It was created to fill in for the tuba in marching bands because a tuba could not be played while it's user marched. Most people consider it an obsolete instrument since a tuba only need be outfitted with a strap to enable it's use in a marching band. The Sousaphone is considered inferior to the tuba in sound quality and is usually only seen at high school sporting events where it's lower cost and light weight outway it's poor sound.

No, it is a brasswind instrument created at the request of the "composer" John Philip Sousa who wrote most of America's popular marching band music. It was developed by adapting the bell of the Helicon (a form of tuba that wraps around the body and rests on one shoulder to allow playing while marching or on horseback.) The first Sousaphones had bells that point straight up in the air and could also be turned to point forward. Later versions had the bell arranged to rotate left or right but was tipped forward at a fixed angle (as it is currently.)
Sousaphones are in use worldwide and are made by many musical instrument companies. The Sousaphone is considered slightly different to the Tuba in sound quality, but can play exactly the same notes. Some Tubas have more valves than Sousaphones for increased range and improved intonation.
Sousaphones are seen in high school and college marching and "Pep" bands, Military Bands, Jazz, Rock and Funk bands, where the comfortable playing position and sound projection are appreciated. Helicons are still in production and are very popular in Southern European brass bands.