Facts about Horn Shark

Commonly known as the bullhead shark, the pig shark or the horned shark, they prefer to stay in the depths of the ocean. Their short, blunt head, with high ridges above the eyes, is the primary reason for which they are known as the Horn Sharks They are nocturnal sea creatures which forage only at night, and have a comatose behavior during the day. They belong to the family of Heterodontidae or bull head sharks. Their biological name is Heterodontus francisci, which is derived from the two Latin words, heteros meaning different and odont meaning teeth. 'Francisci' is the name of the species to which they belong.

Features:
These sharks are brown in color with black spots all over their body. The adults can reach up to a length of 4 feet and weigh up to 10 kg. The adolescent ones have been recorded to reach up to a length ranging between 1 to 1.6 feet. Their spines are located in their first and second dorsal fins and they also have an anal fin. An interesting fact about the horn shark is that it has five gills. More than one type of tooth is present in their dentition. This is the primary reason for its genus name; Heterodontus. It has small teeth in the front of its jaw and crushing molars behind them.

Geographical Distribution:
With whatever records that are available, these sharks are considered as natives from the seas of Central California to Gulf of California, Mexico. Some eminent sea researchers have also suggested the probability of the presence of these sharks in the seas of Ecuador and Peru.

Discovery:
Their genus was described by Blainville in 1816 while their species was described by Girar in 1855.

Habitat:
Horn Sharks do not travel much. They have a small home range of around 3300 square feet. The maximum distance that has ever been recorded for a horn shark to have traveled out from its habitat is 10 miles. These sharks inhabit in the warm waters and the subtropical waters of the Eastern Pacific. They prefer to stay in waters with temperature above 68 Fahrenheit (20 degree Celsius). Contrary to other small sharks, they prefer to stay in the depths of the ocean and thus also fall in the category of 'benthic' sharks. In normal sea water they stay at depths of 25 to 40 feet, from the sea level while in the inter tidal zone they go down to a depth of 656 feet. In winters they prefer to stay at least below 98 feet from the sea level to keep their bodies warm. The adolescent sharks which are not much large in size, have been observed to stay at depths in the range of 131 to 492 feet from the sea level. In warm waters they dwell in the shallow part of the continental shelf while during the winters they inhabit in the rocky reefs, caves, crevices, caverns and kelp bed.

Food:
Horn sharks are carnivorous sea creatures. They mainly feed on sea urchins, which is the reason for their stained purple teeth. They also feed on other benthic invertebrates, mollusks, crustaceans and sea creatures like gastropods, crabs, shrimps, squids, polychaetes, small clams, sea anemones and starfishes.

Reproduction:
Horn Sharks fall into the class of oviparous sea creatures. The females have a very distinctive way of laying their eggs in spiral egg cases which they wedge into crevices. The eggs generally hatch in 7 to 9 months. The breeding season is generally between the months of February to April during which the females lay two eggs every 11 to 14 days. Generally 24 eggs are released by a single female horn shark in a season. They mate during the months of December and January and the females start releasing their eggs just a few weeks after the mating.

Reaction to humans:
Horn sharks are normally observed by divers during night diving. Horn sharks are generally non reactive to divers. They stay inert and do not pose a threat until they are harassed. However it is always advisable for divers who want to observe horn sharks to stay cautious around their dorsal spines. Till date there has just been one recorded incident of a human having suffered a bite from a Horn shark.

Horn sharks are presently listed under the "Data Deficient" list in the World Conservation Union. The main problem lies in identifying the horn sharks from other varieties of sharks with similar features. Though they are not among those sea creatures who are hunted primarily for food, but they often get caught as a by-catch in fishing expeditions. It may not be easy to identify them because of the insufficient information available to classify them differently; however a chance cannot be taken. They are known to only inhabit just a small area of the ocean world and hence there needs to be a more in depth study, to safeguard this breed of sea creatures from extinction.