Male and female sheephead have different color patterns and body shapes. Males are larger, with black tail and head sections, wide, reddish orange midriffs, red eyes and fleshy forehead bumps. Female sheephead are dull pink with white undersides. Both sexes sport white chins and large, protruding canine teeth that can pry hard-shelled animals from rocks. After powerful jaws and sharp teeth crush the prey, modified throat bones (a throat plate) grind the shells into small pieces.
Sheephead hunt actively during the day, but at night, as many wrasses do, they move to crevices and caves and wrap themselves in a mucus cocoon. Predators on the hunt can't detect the fishes' scent through the mucus covers. Sheephead appear to be asleep, but since fishes don't have eyelids, we can only assume they're sleeping.
During the late 1800s, Chinese fishermen caught large numbers of sheephead for drying and salting. Except for brief periods, fishermen didn't target sheephead again until the late 1980s, when commercial fisheries began to supply live fish to Asian markets and restaurants. The fisheries grew rapidly, with sheephead becoming a large share of the catches. Because restaurant aquariums are small, commercial fisheries seek small, pre-adult sheephead, usually females before they've reproduced. To control the catches of sheephead and prevent overfishing, the California Department of Fish and Game in 2001 established regulations that restrict the catch size of sheephead and the areas where these fish may be caught.
During mating season (between July and September) male sheephead become territorial and defend their spawning territory. Dominant males lead the females in a circular pattern as they broadcast sperm and eggs, respectively. If a smaller male approaches, the male interrupts spawning activity to chase away the intruder. The females spawn between 36,000 and 296,000 eggs, which hatch into larvae. The young of the year sheephead don't resemble adults; they're a bright reddish orange with large black spots on their dorsal and upper tail fins and a white stripe running the length of their bodies.
All sheephead are born female. Most of them change to males following environmental clues we don't fully understand. In 1990, Robert Cowen studied sheephead in four sites where the availability of food varied. In the area with the most food, females changed sex at about 13 years old and lived about 21 years. In the area with the least food, females changed sex at five to six years old and lived about nine years. At least in these two areas, the females changed sex about two-thirds of the way through their life spans.