The Horn Shark (Heterodontus francisci) is a small, bottom-dwelling species belonging to the ancient Bullhead Shark family, Heterodontidae. It is endemic to the warm-temperate and subtropical continental shelf of the Eastern Pacific Ocean, ranging from central California into the Gulf of California. This nocturnal, slow-moving predator hunts the rocky reefs and kelp forests of its habitat.
Maximum and Average Measurements
The Horn Shark is not a large species. The maximum recorded length is approximately 122 centimeters (4 feet) in total length, though such specimens are uncommon. Most adult individuals typically measure closer to an average length of 96 to 97 centimeters (3.1 to 3.2 feet).
The typical weight for a fully grown adult Horn Shark ranges up to about 10 kilograms (22 pounds). Sexual size dimorphism is present, with females often reaching a greater maximum size than males. While males typically mature between 56 and 61 centimeters, females can reach up to 96 centimeters or the maximum 122 centimeters recorded.
Distinctive Physical Features
The shark’s physical profile is defined by a stout, cylindrical body and a short, blunt head, which contributes to its “bullhead” nickname. Prominent ridges are located directly above its eyes, giving the head a distinct, somewhat square-shaped appearance. The most striking features are the two high dorsal fins, each preceded by a sharp, cartilaginous spine.
These protective spines give the species its common name and can be used to deter potential predators. The coloration is typically a blend of dark to light gray or brown, often covered with many small, dark spots that aid in camouflage on the seafloor.
The Horn Sharkâs mouth contains two distinct types of teeth that reflect its diet of hard-shelled prey. The teeth located at the front of the jaw are small and pointed, designed for grasping and securing food. Further back, the teeth are much larger, elongated, and molar-like, specializing in crushing the exoskeletons of crustaceans and mollusks.
Growth Rate and Lifespan
The growth rate of the Horn Shark is slow and highly variable compared to many other shark species. This slow development means the time it takes an individual to reach its full adult size can vary significantly. The size at which an individual reaches sexual maturity is relatively small, with both males and females maturing around 56 to 61 centimeters in length.
Despite their small size at maturity, Horn Sharks are long-lived animals. The age of sexual maturity is estimated to be late in their development, taking several years. In the wild, their estimated lifespan can reach 25 years or more, providing a long period for incremental growth.