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Heterodontus francisci:   (click for more)

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Synonyms
  •  
  • Heterodontus californicus  Herald, 1961: 49. Apparent error for H. francisci, which was cited correctly by Herald on p. 32.
    Other Combinations:  Gyropleurodus francisci (Girard, 1854).
    FAO Names
    En - Horn shark, Fr - Requin dormeur cornu, Sp - Dormilón cornudo.
    3Alpha Code: HEF     Taxonomic Code: 1040100101
    Scientific Name with Original Description
    Cestracion francisci  Girard, 1854, Proc. Acad. Nat. Sci. Philadelphia, 7(6): 196. Holotype: U.S. National Museum of Natural History, apparently lost according to Taylor (1972, Rev. shark fam. Heterodontidae: 47). Type locality, Monterey Bay, California. Not listed in catalogue of USNM shark types by Howe and Springer (1993, Smiths. Contr. Zool., [540]: 1-19). Syntypes possibly USNM 933 (2) according to Eschmeyer (1998, Cat. Fish.: CD-ROM).
    Diagnostic Features
    fieldmarks: Dorsal fins with spines, anal fin present, colour pattern of small dark spots less than one-third eye diameter on light background, no light bar on interorbital space between supraorbital ridges, first dorsal-fin origin over pectoral-fin bases.

    Supraorbital ridges moderately low, abruptly truncated posteriorly; interorbital space deeply concave, depth between ridges less than one-fourth eye length.  Anterior holding teeth with a cusp and a pair of cusplets in adults, posterior molariform teeth strongly carinate and not greatly expanded and rounded.  Pre-first dorsal-fin length 22 to 27%, and anal-caudal space 4 to 8%, of total length.  Lateral trunk denticles small and smooth, area behind first dorsal fin with about 200 denticles per cm² in adults.  Propterygium separate, not fused to mesopterygium.  First dorsal-fin spine directed obliquely posterodorsally in juveniles and adults; first dorsal-fin origin anterior to pectoral-fin insertions, over or slightly behind midbases of pectoral fins and well posterior to fifth gill openings; first dorsal-fin insertion well anterior to pelvic-fin origin and well behind pectoral-fin insertion; first dorsal-fin free rear tip opposite or somewhat anterior to pelvic-fin origins; first dorsal fin moderately high and semifalcate in adults, height 9 to 14% of total length, slightly larger than pelvic fins. Second dorsal-fin origin over or slightly in front of pelvic-fin rear tips, second dorsal fin somewhat falcate and nearly as large as first dorsal fin. Anal fin subangular and weakly falcate, with apex reaching lower caudal-fin origin when laid back; anal-caudal space about equal to anal-fin base.  Total vertebral count 103 to 123, precaudal count 65 to 76, monospondylous precaudal count 30 to 38, diplospondylous precaudal count 32 to 46, pre-first dorsal-fin spine count 12 to 16, count from diplospondylous transition to second dorsal-fin spine 7 to 16.  Egg cases with flat thin spiral flanges diagonal to case axis and no tendrils on case apices; flanges with five turns. A large species, mature between 59 and 122 cm.  Background colour of dorsal surface dark to light grey or brown with dark brown or black spots on body and fins, spots generally less than one-third eye diameter; body without a dark harness pattern; head without a light bar on interorbital surface; small dark spots present below eye on a dusky patch; fins without abrupt dark tips and white dorsal-fin apices; hatchlings without whorls on fins and body, colour pattern as in adults although brighter. 
    Geographical Distribution

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    Warm-temperate and subtropical waters of the eastern Pacific: USA (Central and southern California), Mexico (Baja California, Gulf of California), and probably Ecuador and Peru. Off the USA it is most common off southern California but ranges to Monterey Bay and may occasionally penetrate as far north as San Francisco Bay (where it is not resident) during northern influxes of warm water.
    Habitat and Biology
    A common benthic and epibenthic shark, found on the eastern Pacific continental shelf,most abundantly at depths from 2 to 11 m but ranging from the intertidal down to at least 150 m. Found on rocky bottoms including reefs, kelp beds, sandy draws between rocks, and on sand flats. On rocks it often occurs in deep crevices and small caves, and ventures far into large underwater caverns. Juveniles shelter on sandy bottom, often near algae, rocks, detritus, or in feeding holes excavated by bat rays (Myliobatis californica).

    The horn shark is sluggish, nocturnal, and mostly solitary, though small aggregations have been seen by divers. It is seldom seen moving during the daytime but commonly has its head in a crevice. Shortly after dusk this shark becomes active and apparently feeds mostly at night, but ceases activity after dawn. Adults tend to return to the same resting place every day, but range at night over a small home range of roughly 0.1 hectare.According to Michael (1993) these sharks migrate into deeper water in winter, but it is uncertain if this occurs in the tropical part of their range.Experimentation with captive horn sharks indicates that their diel activity pattern is controlled by light intensity. The broad, muscular paired fins of the horn shark are used as limbs for clambering on the bottom, and are highly mobile and flexible. Swimming is slow and sporadic.


    Courtship and copulation have been observed in captivity. The male horn shark chases the female until the latter is ready, then both drop to the bottom. The male grabs the female's pectoral fin with his teeth and inserts a single clasper in her cloaca; copulation lasts 30 to 40 min. One to two weeks later eggs are laid by captive females, one of which laid two eggs per day at 11 to 14 day intervals for four months. In nature these sharks mate in December or January and females drop eggs in February to April. Females normally deposit eggs under rocks or in crevices between them, but in captivity they drop eggs on the bottom where the contents of egg cases may be subsequently sucked out and eaten by these sharks. Eggs can be readily hatched in aquaria and take 7 to 9 months to hatch; the young begin to feed a month after hatching.

      The horn shark feeds on benthic invertebrates, including sea urchins (echinoids), crabs, shrimp, isopods, sipunculid worms, anemones, bivalves, gastropods (possibly abalone), cephalopods (octopuses), but less commonly on small fish including pipefish (Syngnathidae) and blacksmith (Chromis punctipinnis, Pomacentridae). According to Michael (1993), the active diurnal blacksmith is eaten at night by the horn shark while it is resting on the bottom.Predators are little known: a Pacific angelshark (Squatina californica) has been filmed as swallowing small horn sharks and spitting them out alive, possibly because of their strong spines.
    Size
    Maximum 122 cm but most adults are below 97 cm. Egg cases 10 to 12 cm long and 3 to 4 cm wide at broad end (not over flanges); length at hatching 15 to 16 cm; males maturing at about 58 to 59 cm and adult at 59 to 84 cm; females mature above 58 cm.
    Interest to Fisheries
    Interest to fisheries minimal, probably utilized or formerly utilized for fishmeal as a bycatch of the shrimp fishery and other bottom trawling operations in Pacific Mexican waters. It has been captured by divers for sport and for its large fin spines, which are made into jewellery; decreases in numbers of horn sharks have been noted in areas with intense diver activity in southern California.
    Local Names
    USA : California bull-head shark ,  Bullhead shark ,  Horned shark .
    Remarks
    Michael (1993) had a photobraph and brief account of what may be an undescribed bullhead shark in the southern Gulf of California, which he termed the Cortez bullhead shark (Heterodontus sp.). According to Michael it is similar to H. francisci and Heterodontus mexicanus but differs from both species in having higher, more falcate dorsal fins, no dark spots, a lighter abdomen, and no light line on the interorbital space. It has low supraorbital ridges as in H. mexicanus. The species has not, to the writer's knowledge, been collected, so its status is treated as uncertain here pending detailed comparison of material with the sympatric H. mexicanus and H. francisci.
    Threat to humans: Horn sharks are often harassed and grabbed by divers, but when provoked may swim after their assailants and bite them. These sharks are kept in many public aquaria in the United States. They are hardy, attractive, readily maintained, will breed in captivity, and have been displayed for many years.
    Source of Information
    Sharks of the world An annotated and illustrated catalogue of shark species known to date. Volume 2 Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes). Leonard J.V. Compagno 2001.  FAO Species Catalogue for Fishery Purposes. No. 1, Vol. 2. Rome, FAO. 2001. p.269.
    Bibliography
    Applegate  et al.,  1979. 
    Beebe & Tee-Van, 1941
    Chirichigno, 1980
    Compagno, 1983, 1984
    Compagno, Krupp & Schneider, 1995
    Daniel, 1928
    Feder, Turner & Limbaugh, 1974
    Limbaugh, 1963
    Michael,1993
    Miller & Lea, 1972
    Nelson & Johnson, 1970
    Roedel & Ripley, 1950
    Segura-Zarzosa, Abitia-Cárdenas & Galván-Magaña, 1997
    Smith, 1942
    Taylor, 1972
     
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