[Phylum: Chordata] [Class: Chondrichthyes] [Order: Heterodontiformes] [Family: Heterodontidae]
Some of the horn shark species actually have horns that contain venom. But, H. francisci is mostly a harmless and solitary creature that hunts under the cover of darkness.
This guide explains where Heterodontidae live, how their behavioural patterns link with bullhead sharks, what horn sharks eat, and how they reproduce.
The Heterodontidae family of small sharks inhabits several key areas of the Eastern Tropical Pacific Ocean (ETPO), including:
So, they prefer to live in warm-temperate and subtropical water. Some reports have also placed them as far south as Peru (unconfirmed).
In fact, the continental shelves in these regions create the ideal conditions for the horned shark, along with several other small Heterodontiformes, such as:
Even so, horn sharks are less tolerant of chilly habitats and they prefer water temperatures above 20° Celsius (68° Fahrenheit).
In general, you will find the horn shark living around shallow rocky outcrops and areas where large brown seaweed grows in abundance (e.g. kelp beds above sandy bottoms).
Depths of twelve (12) metres (40 feet) make ideal hunting grounds for this species. But, they have also been seen in much deeper water - down at 150 metres (499 feet) - during their winter migration pattern.
You can characterise all bullhead sharks by the shape of the head - short and wide. But, other noticeable features include the blunt snout and proud ridges situated above the eye sockets (supraorbital).
Horn sharks do not have any nictitating membranes (third eyes) for protection. Instead, they have tiny spiracles to help with oxygenation.
A long flap divides the nostrils into the inflow (encircled by a groove) and the outflow openings.
The outflow connects to the small, curved mouth with labial furrows situated at the corners.
Here's the thing:
The upper jaw contains 19 to 26 tooth rows and there are 18 to 29 tooth rows in the lower jaw.
Reef-dwelling horn sharks use their small, pointed front teeth for grabbing prey and then holding it in the mouth.
One interesting fact about the horn shark species is the way they use their back teeth. Being flatter means they can crush hard-shelled food, such as hard-shelled aquatic crustaceans and marine mollusks.
Two sickle-shaped (falciform) dorsal fins bear frontal spines on top of the typical tubular body shape - as seen in many of the different shark species. In fact, the average weight of a horn shark is around 10 kg (23 pounds).
This horned shark is one of the smaller specimens, rarely growing more than one (1) metre in length (4 feet). The stout body contains scales that are small and coarse. This 'roughness' provides them with good protection against their natural predators (e.g. eagles, elephant seals, and large pelagic sharks).
Being a nocturnal species, it spends much of the day hidden inside caves and sheltering underneath rocky crevices at the ocean floor. But, as darkness falls they will emerge to feed on:
Pro Tip: Heterodontus francisci need high concentrations of calcium in the wild (animals with hard exoskeletons). So, feed them shrimps and squid if you keep horn sharks in captivity to increase their calcium intake.
Like many ocean species, the female horn shark is an oviparous fish and will lay its eggs after mating. In fact, they can lay more than twenty eggs in a single breeding season (February to April).
It takes up to ten (10) months for the embryos to develop. But, this time period is dependent on the temperature of the water. When full development is complete, baby horn sharks measure around seventeen centimetres long (7 inches).
Interesting Fact: Baby horn sharks develop sharp spines immediately after birth. This helps to protect them from being eaten as prey, for example by angel sharks (Squatina squatina) or sea bass.
The average lifespan for horn sharks is about twenty five years. It's difficult to get accurate population data, as the IUCN lists them as being 'Data Deficient'.
Nonetheless, commercial fisheries do not generally target these types of sharks. But, human activities are having a negative impact on horn shark populations, including:
Pro Tip: It's easy to confuse horn sharks with the much feared bull shark (Carcharhinus leucas). Another section contains bull shark facts and information to help differentiate the two classifications.
Note: The short video [2:59 seconds] presented by Deep Marine Scenes contains footage of the horn shark (Heterodontus francisci) swimming and feeding in its natural habitat.