page_title: Horn shark
section_title: Life history
hierarchical_section_title: Horn shark / Biology and ecology / Life history
caption_attribution_description: Egg case of the horn shark (Heterodontus francisci), from Morro Bay State Park.
context_page_description: The horn shark is a species of bullhead shark, in the family Heterodontidae. It is endemic to the coastal waters off the western coast of North America, from California to the Gulf of California. Young sharks are segregated spatially from the adults, with the former preferring deeper sandy flats and the latter preferring shallower rocky reefs or algal beds. A small species typically measuring 1 m in length, the horn shark can be recognized by a short, blunt head with ridges over its eyes, two high dorsal fins with large spines, and a brown or gray coloration with many small dark spots.
  Slow-moving, generally solitary predators, horn sharks hunt at night inside small home ranges and retreat to a favored shelter during the day. Their daily activity cycles are controlled by environmental light levels. Adult sharks prey mainly on hard-shelled molluscs, echinoderms, and crustaceans, which they crush between powerful jaws and molar-like teeth, while also feeding opportunistically on a wide variety of other invertebrates and small bony fishes. Juveniles prefer softer-bodied prey such as polychaete worms and sea anemones.
context_section_description: Mating in the horn shark occurs in December or January, on a possibly annual reproductive cycle. The male chases the female to indicate interest; once she is ready both sharks settle on the bottom, where the male grips the female's pectoral fin in his teeth and inserts one of his claspers into her cloaca. After 30–40 minutes of copulation, the pair disengages and the female spins with her snout in the sand for another 30 minutes. From February to April, the females lay a maximum of 24 eggs two at a time once every 11–14 days, in water 2–13 m (6.6–42.7 ft) deep. The egg case has two flanges spiraling around it, and thus may take the female several hours to deposit. At first the case is soft and light brown, and over a few days it hardens and darkens in color. Not including the flanges, the case measures 10–12 cm (3.9–4.7 in) long and 3–4 cm (1.2–1.6 in) wide; sharks from the Channel Islands produce longer egg cases than those from mainland California, suggesting that they are separate populations.
  One of the few sharks to exhibit parental care, female horn sharks in the wild pick up their eggs in their mouths and wedge them into crevices. However, in captivity the eggs are simply dropped on the bottom and may later be cannibalized. The eggs hatch in 6–10 months; at emergence the young measure 15–17 cm (5.9–6.7 in) long. Newly hatched sharks are provisioned with an internal yolk sac and do not have to feed until they are a month old, though they are capable of feeding and will accept food during this period. Horn sharks grow slowly and at a highly variable rate that does not correspond to their size; this has frustrated attempts to determine their aging process. Males mature at a length of 56–61 cm (22–24 in) and females at a length of at least 58 cm (23 in). Individual sharks have lived to over 12 years old in captivity, and there exists an unconfirmed report of a shark reaching 25 years of age.
caption: The spiral-flanged egg case of a horn shark; the shape allows the egg to be secured within crevices.
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