You know Lalo Schifrin from his immortal soundtracks, but he also has a career as a very successful jazz musician. Black Widow was an album that Schifrin released in 1976, and it contained some original work and some covers where he put his own spin on some standards... and John Williams' theme to Jaws.
Schifrin's version of the Jaws theme bears only the most passing resemblence to Williams', and only at the beginning of the track. After that the sound becomes something much more like the great 60s and 70s scores Schifrin did, like something out of Magnum Force.
The track became a hit at the disco, and so Top of the Pops featured it on the show, with the Legs & Co dancers doing their own interpretation of Jaws. It's weird.