Thrasher

Thrashers are hostile aquatic mobs that spawn in cold and frozen oceans. Thrashers are blind, and shoot sonar waves to detect their enemy. If a sonar wave hits a target, the Thrasher will proceed to attack it. Thrashers attack by grabbing prey in their mouths, and violently shaking them. Hitting a Thrasher while in its mouth will stun it for a few seconds. Great Thrashers are larger, stronger variants of Thrashers which spawn in Deep Frozen Oceans with a 25% chance.

Trivia

 * The sound effects made by the Thrasher are edited recordings of one of the developer's dogs growling and barking.
 * In one of the sounds it makes, you can hear his collar.
 * The dog's name is "Dixon".