The silky shark is one of the most abundant open water shark species. Its genus name, Carcharhinus, is derived from the Greek words “karcharos” (sharpen) and “rhinos” (nose). Size segregation may be present within this species as they have been observed traveling with others of their own size. They are generally solitary but have been known to travel in loose aggregations or groups. And the juveniles primarily travel in groups until sexual maturity, a strategy that is thought to protect them from larger predators. The adults can be social with conspecifics and often intermix with schooling scalloped hammerheads (Sphyrna lewini). Quick-moving and aggressive, they have been observed using threat displays such as a raised head, arched back, and lowered tail. This species transitions between different habitats during various life stages. Juveniles live in nursery grounds, young adults migrate offshore to deeper waters, while adults return seasonally to continental and insular shelf areas. The silky shark is listed as “Vulnerable” on the IUCN Red List and is vulnerable to over-fishing due to its long gestation period, low number of offspring, and slow growth rate. They are often caught as by-catch in tuna fisheries. Their predators include killer whales (orcas), large sharks, and humans. Humans use flesh and fins for food, hide for leather, and the liver for oil. It's estimated that the population has decreased by 85% over the course of a 19-year period (1984-2005) and continues to decrease.
  • Size

    • Common length for adult female is 7-7.5 feet (2.1-2.3 m); common length for adult male is 6-7 feet (1.8-2.1 m).
  • Diet

    • Generalist carnivore; diet consists of various species of fish, squid, pelagic crabs, nautilus and chub mackerel.
  • Range

    • Found on continental and insular shelves, over deep water reefs and in open ocean, slope and shallow, coastal waters at depths between 59-164 feet (18-50 m).
  • Habitat

    • Occurs in tropical and subtropical waters in the Atlantic, Pacific and Indian Oceans.

Physical Characteristics

  • Body is large and slim with a moderately long, rounded snout, large eyes, and small jaws.
  • Coloration can vary greatly in this species. Dorsal surface may have a bronze tint and can range in color from dark brown to blue-gray or dark gray. Ventral surface is white
  • Defining characteristics include small, densely-packed dermal denticles and notched, or serrated, teeth.
  • Size and density of the dermal denticles gives the shark’s skin a smooth or “silky” texture.
  • First dorsal fin is small and rounded. Second dorsal fin is small with a long, trailing tip. Pectoral fins are elongated and sickle-shaped.
  • Common length for adult female is 7-7.5 feet (2.1-2.3 m); common length for adult male is 6-7 feet (1.8-2.1 m).
  • Maximum recorded length is 11.5 feet (3.5 m).
  • Maximum recorded weight is 802.4 pounds (364 kg).

Animal Fact

A silky shark's maximum recorded length is 11.5 feet (3.5 m).

Diet / Feeding

  • Generalist carnivore; diet consists of various species of fish, squid, pelagic crabs, nautilus and chub mackerel.
  • Variation in diet depends on abundance and availability of prey. Opportunistic feeder when prey abundance is low, often consuming a wide variety of prey from different habitats and depths in the open ocean.
  • Juvenile feeds primarily on jumbo squid while adult feeds on red crabs, chub mackerel, yellowfin tuna, albacore, mullet and porcupine fish.
  • Highly migratory species, often following the movements of schooling fish such as tuna.

Range / Habitat

  • Occurs in tropical and subtropical waters in the Atlantic, Pacific and Indian Oceans.
  • Western Atlantic Ocean from Massachusetts to southern Brazil including the Gulf of Mexico and the Caribbean Sea to Uruguay.
  • Eastern Atlantic Ocean from Madeira, Spain to northern Angola, S. Paul’s Rocks, and Cape Verde.
  • Western Indian and the Red Sea from Tanzania to Mozambique including Madagascar and the Comores.
  • Eastern Indian Ocean from the Maldives and Sri Lanka to western Australia.
  • Indo-Pacific from China to New Zealand and the Caroline, Hawaiian, Phoenix, and Line Islands.
  • Eastern Pacific Ocean from southern Baja California, Mexico to northern Chile.
  • Highly migratory species.
  • Found on continental and insular shelves, over deep water reefs and in open ocean, slope and shallow, coastal waters at depths between 59-164 feet (18-50 m).
  • Prefers warmer waters of about 74°F (23°C)

Reproduction & Growth

  • Reproductive maturity is reached at 7-9 years of age and 7-7.5 feet (2.1-2.3 m) in length in female; 6-7 years and 6-7 feet (1.8-2.1 m) in male.
  • Sharks in the Indian Ocean and in the Pacific Ocean achieve maturity at younger ages and at smaller sizes than sharks in other areas (approximately two years younger and 1-2 feet (0.3-0.6 m) shorter).
  • Viviparous; give birth to live young.
  • Breeding takes place year-round in tropical waters and in summer months (June, July and August) in warm-temperate waters.
  • Average gestation period is 12 months.
  • Litter number varies by geographic location, litter size can range between 2-14 pups.
  • Pups may spend first few months of life near reefs or in nursery areas until their first winter when they move to open ocean.

Sources

www.fishbase.org

www.iucnredlist.org

www.arkive.org

www.floridamuseum.ufl.edu

www.flmnh.ufl.edu/fish

www.animaldiversity.org

Grzimek’s Animal Life Encyclopedia. Thoney, D. A. and Loiselle, P. V.

Sharks and Rays of Australia. Last and Stevens

Buy Tickets