Swordfish are the sole member of the family Xiphias. While they share the same prominent rostrum as other billfish, their bill is much larger in size compared to the size of their body, and much flatter. They are stocky fish with round bodies and large eyes, as well as a crescent shaped dorsal fin and no scales. Swordfish spend most of their time thousands of feet deep at the bottom of the ocean, coming to the surface at night to hunt. Swordfish have the unique ability to live thousands of feet below the surface. No other billfish display this behavior, nor have the capability to do so. Special organs in their bodies allow swordfish to direct their internal heat towards their brain and eyes, allowing them to see in pitch black and near freezing conditions.