Common Names: Horn shark, California horn shark

Latin Name: Heterodontus fransisci

Family: Heterodontidae

Identification: Supraorbital crests (brow bones) moderately high. Small dark spots on tan or grey body (spots occasionally absent). Large, blocky, pig-like head. Dorsal spines present, terminating well below tips of dorsal fins. Pectoral fins large. Jaw contains anterior, pointed, clutching teeth and  rear molars. Dentition changes with age (adults have more prominent molars).  

Size: Maximum length 120cm.

Habitat: Rocky reefs and Kelp forests. Juveniles often in open sandy areas.

Abundance and distribution: Central California to the Sea of Cortez and possibly South America .

Behavior: Nocturnal. Hides in crevices or caves during the day venturing out to forage at night. May swim freely but is usually seen sluggishly moving along the bottom on its muscular pectoral fins. Hunts for Urchins, crabs, worms, anemones, and bony fishes.

Reproduction: Oviparous. Lays a distinctive auger shaped egg case with two threadlike filaments extending from one end. Egg hatches in 7 to 9 months.

Observations: I have a friend in Avalon who regularly encounters Horn shark egg cases and places them in his toilet cistern until they hatch safely. He then releases them back into the ocean giving them an edge on the rest of the food chain. (Avalon utilizes salt water in its toilets to save its limited fresh water supply).  

Photographs: Avalon, Catalina Island , California .

Similar species: Mexican bullhead shark - Heterodontus mexicanus, Cortez bullhead shark – Heterodontus sp. Both sharks potentially share the south range of the California Horn shark.

Reaction to divers: Easily approached. Remains motionless unless molested. Caution should be taken around dorsal spines.

Diving logistics: Most easily observed whilst night diving. Catalina offers an excellent opportunity to encounter this shark. Air and equipment can be obtained on the pier in Avalon for shore diving purposes. Head out on the road past Lovers Cove South of town and enter from the beach. This is a long hike if you’re wheeling your gear along in a rented cart. Small Horn sharks are usually present in around 30ft of water. The Dive Park at Casino Point right in Avalon may also be a reasonable place to look at night but this area gets too much traffic during the day for reliable sightings.