First Day at the JL/SA: Sinister Swimmers

The next episode unfolding during the first day at the JLA and JSA are tales told by Earth-One's Aquaman and Earth-Two's Flash. What menace did they each face, and how did they respond accordingly?

Turns out Aquaman is alerted by his finny friends to a dangerous creature swimming through the seas, zapping sea life and turning them to glass. Turns out this an Appellaxian named Glass-Man in order to prove dominant in his element as a testimony to his claim as deserved sovereign of his home world.

However, the King of the Sea quickly dispatches his foe by commanding his undersea allies to create another vibrations to shatter Glass-Man's form.

For the Flash, who is off on a sea scavenging adventure aiding a kind fellow against a pack of criminals, the Fastest Swimmer Alive faces an odd foe. A seemingly sentient man-eating shark attempts to feast on Flash, but instead finds he's bitten off more than he can chew...so to speak. Then the hero makes quick work of the crooks. We continue we a Mercury Monster and an inky octopus from the Nile, and their masters behind the scenes...