Six short rephrasings
A walrus uses its tusks to climb onto the ice and to keep itself safe.
The walrus’ tusks help it climb onto the ice and defend itself.
With its tusks, a walrus climbs onto the ice and guards itself from danger.
The walrus uses its tusks to get up on the ice and to protect itself.
Climbing onto the ice and defending itself, the walrus relies on its tusks.
Its tusks let the walrus climb the ice and defend against threats.