Generally nocturnal and solitary, during the day the California horn shark conceals itself amongst rocks, kelp or within crevices or caves, and emerges at dusk to feed (2) (5). This species takes a variety of bottom-dwelling marine invertebrates, including sea urchins, crabs, gastropods, shrimp, squid, sea stars and probably abalone; it will also take small fish (1) (5). Prey is captured by rapidly protruding the upper jaw, which bears pointed teeth at the front that act like a chisel to chip the victim away from the substrate. The rapid opening of the mouth then creates a powerful suction that pulls the prey inside, where it is crushed by the flattened, molar-like teeth at the rear of the jaws. In order to aid the removal of strongly attached prey, the California horn shark will also use its body as a lever, performing a headstand in the water, grasping the prey in the jaws and pulling the rear of the body down while bracing against the pectoral fins, which are in contact with the substrate (6). The adult California horn shark hunts within a relatively small home range, usually no larger than 1000 square metres and may occupy the same site for many years (1).
The California horn shark mates in December or January. After one or two weeks, the female starts laying eggs, producing two eggs at 11 to 14 days intervals for around four months. The egg is roughly conical in shape with a spiral flange running around the outside, which enables the female to wedge it into a crevice, thereby making it difficult for predators to access. The embryos take between 6 and 8 months to develop according to water temperature, and emerge measuring between 15 and 17 centimetres in length (1). After hatching, the young sharks shelter in areas of shallow water, on sandy bottoms near kelp or rock, or in feeding holes excavated by bat rays (Myliobatis californica) (2). When the immature sharks reach between 35 and 49 centimetres in length, they migrate to deeper waters, between 40 and 150 metres, eventually migrating back to relatively shallow water when mature. Such segregation of age classes helps to reduce competition for food and habitat. Sexual maturity is reached at lengths of around 58 centimetres and the maximum recorded lifespan is 25 years (1).