The Silky shark (Carcharhinus falciformis) is known for the smooth texture of its skin. They are highly migratory, and we are lucky enough that Silky sharks spend a portion of their time here in Jupiter Florida. Check out some Silky action by clicking this to watch one of our videos. (seen here Silky sharks and Rhonda the blind Dusky shark)
Photo: © 2018, Harry Stone, Planet Shark Divers, all rights reserved.
Family: Carcharhinidae – Requiem sharks
Common Name– Ground Sharks
Common Name– Requiem Sharks
Status: IUCN Red List VULNERABLE
Average Size and Length: The Silky shark has a slender, streamlined body and typically grows to a length of 8 ft 2 in. Pups are born between 2.2-2.8 feet, mature males between 6.1 and 7.1 feet, and mature females 6.9-7.5 feet. The longest recorded Silky shark reached 10.8 feet in length.
Average Weight: The average weight of an adult Silky shark is 420 pounds. One documented account of a Silky shark reaching over 600 pounds.
Current Rare Mythical Sightings: Here In our home Jupiter, Fl, we frequently dive with Silky sharks during the summer and fall months. Check out our PSD videos to watch them in action!
Teeth and Jaw: Silky sharks have a long, flat-rounded snout with a smaller jaw. Silky Sharks have both upper jaw and lower jaw symphyseal teeth. Their upper teeth are oblique-cusped and serrated. Check out this video here
Head: Silky sharks have a small head, a long flat-rounded snout and very large eyes.
Dermal Denticles: Researchers scan them using scanning electron microscopy (SEM). Small, tightly packed and over-lapping giving the hide a smooth or “silky” texture, hence the common name.
Demographic, Distribution, Habitat, Environment and Range: Silky sharks love warm, tropical waters all over the world. Of the three most common Pelagic sharks (the other two the Oceanic Whitetip and the Blue shark) they are the most common sharks found in the “Pelagic Zone” which are continental shelves with depths of 660 feet all the way to 1,640 feet or more (unreferenced sources claim to have caught one at a depth of 12,400 feet). Often times, they are seen near the surface as well. They prefer water temperatures of 20 to 30 degrees Celsius (60 to 86 degrees Fahrenheit).
Diet: A Silky shark’s diet mostly consists of bony fish (especially Tuna), octopus, and squid. Silky sharks have been known to follow their prey for days and can go weeks without eating. They are persistent and resilient, being that they are living in in oceanic pelagic zone.
Ram-Suction Index: A Silky shark is ram-feeding. The attack prey with lighting fast speed and wide-open mouths.
Aesthetic Identification: A Silky shark tends to be long and slender, with slightly shorter dorsal fin (top) with a curving rear margin, its tiny second dorsal fin with a long free rear tip, and its long, sickle-shaped pectoral fins, and elongated pectoral fins.
The Silky shark is a deep, metallic bronze-gray above and counter-shaded white below. They are named for their silky, shiny appearance as they glide through the water. Check out our Silky Shark videos here to see their silky appearance in action!
Biology and Reproduction: The Silky shark is viviparous. Silky sharks reproduce throughout the year, except in the Gulf of Mexico, where it follows a seasonal cycle. Females give birth to litters of up to 16 pups annually or biennially.
Newborn Silky sharks spend their first months in relatively sheltered reef nurseries on the outer continental shelf, growing substantially before moving into the open ocean.
Behavioral Traits, Sensing and Intelligence: They have an extremely strong sense of hearing. This acts as a great advantage for locating their preys. The Silky shark is able to localize the low-frequency noises generated by other feeding animals, and, by extension, sources of food. Silky sharks have been known to follow their prey for days and can go weeks without eating. They are persistent and resilient, being that they are living in in oceanic pelagic zone.
Silky sharks have complex, social behaviors. Juvenile or younger silky sharks are known to form large, loosely organized aggregations, possibly for mutual defense. During migrations, over a thousand individuals may gather. These groups are generally segregated by size, and in the Pacific research suggests also by sex. Silky sharks within a group have been observed to “tilt”, presenting their full lateral profile towards each other, as well as gape their jaws or puff out their gills. On occasion, Silky sharks have also been seen suddenly charging straight up, veering away just before reaching the surface and gliding back down to deeper water.
LATEST RESEARCH: Mote Marine Laboratory scientists and their Cuban colleagues are celebrating the publication of a study on the movement of three female silky sharks (Carcharhinus falciformis) tracked by satellite-linked tags off the Caribbean coast of Cuba. This study is the result of the first expedition in Cuban waters to satellite-tag sharks, in accordance with Cuba’s National Plan of Action for Sharks, adopted in late 2015.
In a special Cuba edition of Bulletin of Marine Science, the peer-reviewed study sheds light on the life of this vulnerable species.
The study abstract was published online this month.
Speed: Tagged Silky sharks have been recorded to swim up to speeds of 37 miles per hour.
Silky Shark Future and Conservation: According to IUCN: “The Silky Shark (Carcharhinus falciformis) is an oceanic and coastal-pelagic shark with a circumglobal distribution in tropical waters. It is a target or bycatch species in pelagic tuna longline and purse seine fisheries where it is taken in high numbers. Silky Shark is one of the three most traded shark species in the global shark fin trade. Estimates of trends in abundance over three generations (45 years) from standardized catch rate and spawning biomass indices show declines of Silky Shark in the Eastern Central and Southeast Pacific Ocean, Western Central Pacific Ocean and the Atlantic Ocean. Across all three ocean regions, there are the major uncertainties in estimates of catch rate and population changes, and an inability to conclusively attribute any declines solely to fishing mortality as there is some potential for environmental influences on catchability and sampling artifacts. The weighted global population trend estimated a 47-54% decline over three generations. This reflects the proportionate contribution of each region’s Silky Shark population change. The estimated level of decline and the uncertainties in the data warrants a global status of Vulnerable. This assessment should be revisited when more definitive catch data and stock assessments become available”.
Silky Shark Recorded Attacks on Humans: The Silky shark is potentially dangerous because of it’s persistent and inquisitive nature, but not a huge threat to humans. We are much more of a threat to the Silky shark.