What are the sensitive whiskers around a walrus’s muzzle called?

The sensitive whiskers around a walrus’s muzzle are called vibrissae.

A walrus has hundreds of stiff, highly innervated vibrissae arranged in bundles around its snout. These bristles are not merely ordinary hair: nerves at their bases help the animal detect movement and texture in the water or seafloor sediment.

Walruses commonly use their vibrissae while searching for clams, worms, and other bottom-dwelling invertebrates. They can sweep their muzzles across the seabed and identify prey even when visibility is poor. The whiskers are especially useful because walruses often feed in dark or cloudy underwater conditions.

Vibrissae occur in many mammals, including cats, seals, and rats, so “whiskers” is a familiar informal term. A common mix-up is to confuse walrus vibrissae with the tusks: tusks are elongated canine teeth, whereas vibrissae are sensory bristles.