Still want to know why the males are shy of letting other males see them using the sponge!
*P*E*A*C*E*
Bottlenose dolphins from an extended family in Australia’s Shark Bay have taken to protecting their noses with pieces of sponge when foraging for fish on the abrasive sea bed.
Those males that use sponges for hunting do so discreetly and avoid other male dolphins.

Amazing!! The only explanation I can think of for the "sponge-shyness" is that it could be seen as a sign of weakness that your snout is not hard enough.
I suppose that you could compare it to how some macho humans will refrain from wearing gloves or a helmet in order to prove they're tough.
Macho dolphins
They just don't want other males to steal the sponge they found after foraging for so long.
