Sea Shell Oil is a pun on Shell Oil. Sharkskin suits, the must have of any snappy male dresser at the time, were not actually made from sharks. The fabric weave is meant to emulate the texture of a shark's skin.
Among the sea creatures Popeye does battle with are a giant clam, a moon jelly, a shark, and a whale.
One of a number of Popeye shorts which were sent off to Asia in the 80's to undergo the infamous redraw and colorization process.