Risso's dolphin
Grampus griseus
Risso's are among the most heavily scarred marine mammals — NOAA describes adults as usually covered in scratches from raking teeth and circular marks from squid, fading the skin from charcoal grey to near-white with age. Look for groups of 10–50 logging quietly at the surface off the Channel Islands, especially on calm October and November mornings.
Scale
About 1.8× as long as an average adult is tall.
A risso's dolphin runs about 10 ft. Drawn beside an average adult human — 5.7 ft standing, the CDC's own U.S. adult average.
Average adult human: 5.7 ft (5 ft 7 in), CDC NHANES U.S. adult average standing height.
Drawn to the same scale. 10 ÷ 5.7 ≈ 1.8.