Long and eel-like, monkeyface-eels sport a bluntly rounded snout, large fleshy lips and two black lines that radiate from behind their eyes. A dorsal fin runs along the eel's back. A lumpy ridge appears on adult monkeyface-eels' heads. Their color ranges from uniform light brown to dark green—some specimens have orange spots on their bodies and orange-colored fin tips.
Monkeyface-eels' body shapes allow them to live hidden in crevices and holes in rocky reefs, rocky tidal zones and kelp forests. These fish don't move around much, seldom traveling more than 15 feet (4.6 m) from their home. They can breathe air and, in a moist area, can stay out of the water for at least 35 hours.
The commercial fishery for monkeyface-eels is insignificant.
Many monkeyface-eels live close to shore. Tidepoolers turning over rocks are likely to see a monkeyface-eel scurry away. Experienced tidepoolers know it's important to return rocks to their original positions so animals can return to their homes.
Shore anglers fish for monkeyface-eels in rocky intertidal and shallow subtidal zones by "poke poling." The fisherman attaches a short piece of wire with a baited hook to a long bamboo pole. He places the bait in front of a hole between the rocks or "pokes" the pole into crevices and holes.
Peak spawning time is from February to April. Fertilization is internal. After mating, a female deposits 17,500 to 46,000 eggs in a mass on subtidal, rocky surfaces. Observers have seen monkeyface-eels guarding the eggs, but they don't know if males or females (or both) guard the egg masses.
Piscivorous (fish-eating) birds such as herons and great egrets prey on juvenile monkeyface-eels. Other predators include cabezon and grass rockfish.