Bullhead sharks (Heterodontiformes) are a small but distinctive group of bottom-dwelling sharks, known for their broad heads, spiny dorsal fins, and quirky appearances. These slow-swimming reef residents are especially beloved by divers for their calm behavior and unusual anatomy. Three species stand out for their popularity: the horn shark of California, the Port Jackson shark of southern Australia, and the Japanese bullhead shark found around East Asia. Each is well-adapted to life on rocky reefs and kelp beds, often spotted resting during the day or cruising quietly along the bottom at night.