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Carcharhiniformes Triakidae (the houndsharks) Jeff Guertin 10/30/07 9 Genera, ~39 species Furgaleus (whiskery shark) - one species Galeorhinus (school shark, oil shark, vitamin shark) - one species Gogolia (sailback houndshark) - one species Hemitriakis (whitefin tope sharks) - four species (plus 2 unnamed) Hypogaleus (japanese tope shark) - one species Iago (bigeye houndsharks) - two species Mustelus (smooth hound sharks, smooth dogfishes, gummy sharks) ~22 species (plus 2 unnamed) Scylliogaleus (flapnose houndshark) - one species Triakis (leopard sharks) - 5 species General Characteristics Small to moderate-sized sharks Some of the most abundant sharks off of Atlantic and Pacific coasts of North America Horizontally oval eyes Nictitating eyelids Anterior nasal flaps Distinctive Features Small rounded teeth Three to four separate cusps First dorsal in front of the pelvic No precaudal pits Caudal fin may or may not have a strong ventral lobe Two large-sized, spineless dorsal fins Anal fin T. semifasciata - distinctive markings provide camouflage against dappled ground; well developed spiracle; sometimes tinged with iridescence M. canis - melanophores; spiracle is only of moderate size; pronounced sub-ocular fold G. galeus - pronounced spiracles; first dorsal much larger than second dorsal Habitat Tropical and temperate seas worldwide Mostly occur on continental and insular shelves a few are deepwater slope dwellers (up to 2000m) None are oceanic Some seasonally migrate Leopard Shark (Triakis semifasciata) - Eastern Pacific (Mexico to Oregon) but mostly in San Francisco Bay Smooth dogfish (Mustelus canis) - Western Atlantic (Cape Cod to Uruguay) Tope shark (Galeorhinus galeus) - Eastern Atlantic (largest inshore native shark in British waters); Oceania, South Africa, South America Food Habits Feed primarily on bottom and mid-water invertebrates and bony fishes Worms, mollusks, crustaceans, octopuses T. semifasciata - hunt in groups, sometimes with smooth-hound sharks Size, Age, & Growth T. semifasciata - born at a length of about 20 cm, max length of 180cm-200cm (avg. 150cm); maximum reported age about 50yrs M. canis - max size roughly 150cm (avg. 122cm); males have a life span of 10yrs, females 16yrs; males mature 2-3yrs and females mature 3-4yrs G. Galeus - max size roughly 190cm for males, 195cm for female; mature ~10-15yrs; life span up to 55 years Reproduction Live bearing (both viviparous and ovoviviparous) Litters range from 1-52 T. semifasciata - migrate seasonally; aplacental viviparity (ovoviviparous); 4 to 33 pups per litter; Gestation is estimated at 10 to 12 months. M. Canis - viviparous; 4-20 embryos of varying ages, not all born at once; ~10 month gestation G. Galeus - aplacental viviparity; produce young every 2 yrs; 6-52 pups/litter Predators Marine mammals Other large fish (Carcharodon carcharias in particular for leopard sharks) Sharpnose Sevengill (Heptranchias perlo) is a primary predator of tope sharks Conservation T. semifasciata - Lower Risk according to IUCN; but actively sought by sport fishermen in the San Francisco Bay Area and in Monterey Bay for food M. canis - Near Threatened according to IUCN; sought by small fisheries but mostly by-catch; often used as lab specimen and in aquaria G. galeus - Vulnerable globally and Near Threatened in New Zealand according to IUCN; commercially harvested Bibliography Carrier, J,, Musick, J., and Heithaus, M. 2004. Biology of Sharks and Their Relatives. CRC Press, Boca Raton. Cailliet, GM (1992). Demography of the central california population of the Leopard Shark (Triakis semifasciata). Australian Journal of Marine and Freshwater Research 43, 183–193. Conrath CL and Musick JA. 2002. Reproductive Biology of the Smooth Dogfish, Mustelus canis, in the Northwest Atlantic Ocean. Environmental Biology of Fishes 64, 367-377. Florida Museum of National History. <http://www.flmnh.ufl.edu/fish/>. Downloaded on 25 October 2007. IUCN 2006. 2006 IUCN Red List of Threatened Species. <http://www.iucnredlist.org>. Downloaded on 25 October 2007. Nelson, J. 1984. Fishes of the World. 2nd Ed. John Wiley & Sons, Inc., New York. Parker, S. 1999. The Encyclopedia of Sharks. Firefly Books, Buffalo. Perrine, D. 1999. Sharks and Rays of the World. Voyageur Press, Hong Kong. Steel, R. 1985. Sharks of the World. Facts on File, Inc., New York.