An instrumental studio jam at the end of the album, this song was titled for The Who's bass player John Entwistle, who was nicknamed "The Ox" for his strong constitution and ability to out-eat and out-drink the other band members. Considering that this song is both powerful and features an amazing bass lead, it is fitting that it's named after him.
Session man Nicky Hopkins played the piano. Because it was an improvised jam, he got a writing credit along with Pete Townshend, Keith Moon and John Entwistle.
Bass player John Entwistle named his side band The Ox.
John Atkins' book The Who on Record: A Critical History, 1963-1998 describes this song as "put together in the studio as an instrumental blowout. Every instrumental and surf artist from the Ventures to Sandy Nelson and Link Wray are simultaneously acknowledged and overpowered by the heavy barrage of heavy riffing, machine-gun drumming, distortion, and feedback.
This instrumental was also the basis for a later song titled "Top Gear" on The Who's 1967 album The Who Sell Out.
On the final bars of the riff, Townsend seems to have sacrificed yet another guitar. Listen amid the acoustic feedback and you'll hear the crackle and buzz of the guitar lead shorting out.
Other instrumentals named after an animal include Fleetwood Mac's "Albatross," Bent Fabric's "Alley Cat," Weather Report's "Birdland," Radiohead's "Hunting Bears," Allman Brothers' "Kind Of Bird, Led Zeppelin's "Moby Dick," Cole Porter's "Song Of The Birds," Herb Alpert's "Spanish Flea," and Yes' "The Fish." To name some of them.
