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The Silky Shark

Silky shark (from Latin Carcharhinus falciformis) belongs to the family of requiem sharks (Carcharhinidae) of order Carcharhiniformes.

Like most of the requiem sharks, the silky shark is a perfect swimmer. This is achieved due to a perfectly slender, streamlined body of a typical shark form covered with soft placoid scales, from which it has taken its name. It is also commonly referred to as Florida shark, wide mouth shark, sickle-shaped shark and the tuna killer because of its fancy to feed on tuna caught in the fishing nets.

The silky shark has typical dark coloration of various shades of bronze, grey, blue and golden-brown on its back and white on its belly. These colors gradually fade with aging. The scales covering the skin are so small, it seems as if they are totally absent. In the sunbeams penetrating the water surface the sharks body gleams with golden-blue.

A distinctive feature of this species is long free rear tips found on anal and second dorsal fins. The first dorsal fin is relatively small and slightly rounded, located in front of the pectoral ones. The caudal fin is rather large with a prolonged upper part protruding at the top. The two long sickle-shaped pectoral fins, which darken at the tips, had determined the Latin scientific name of this shark.

The silky shark is easily distinguishable among the other species: in addition to peculiar silky skin and long free rear tips on dorsal fins this species of requiem sharks has a skin fold in between the dorsal fins and a relatively small fore fin, which is concave at the top and shifted to the back in relation to long pectoral fins. The first pectoral fins base is located in close proximity of the last gill slit.

Relatively big round eyes have a third eyelid the well-developed nictitating membrane. Exceptionally keen hearing allows the silky shark orienting by low-frequency noises coming from potential prey. A highly developed sense of smell, which is typical for all pelagic sharks, is of vital importance because it allows finding sources of food on the open sea.

Such an acute sense of smell of this predator allows detecting the victim within several hundreds of meters that in the context of tough competition might play a crucial role. Thus, a more effective sense of smell of longimanus, also known as the oceanic whitetip shark, detects smells, which pervade in the air, thereby it always reaches the target before its silky and blue peers.

The rather small jaws with sharp saw-edged teeth, which are facing backward, are the perfect weapon suited both for holding down the slippery prey and for effectively cutting it apart. Sharp upper teeth are basically the triangular serrated blades. The lower teeth are smaller, narrower and smooth-edged. The junction between the base and the top of the tooth is well-marked.

The silky or sickle-shaped shark is a large slender fish with a long rounded nose, big eyes and long sickle-shaped jaws on the lower part of its slightly flattened snout. This predator reaches from 2.5 meters up to 3.5 meters in length. The maximum recorded weight is 346 kg. The recent intensive extermination of sharks has resulted in even small specimen of this predator being difficult to encounter. As with most of the recent shark species, males are a bit smaller than females.

The silky shark is an aggressive and a very fast predator. It usually hunts alone, although it can unite into shoals with whitetip, requiem and more rarely with blue sharks and dolphins. It feeds on bottom-lying, pelagic and reef bony fishes, crustaceans and shellfish. It favors the schooling pelagic fish: sardines, grey mullets and mackerels. Its favorite meal is tuna.

Qualifying as species, which migrate for long distances and inhabit predominantly the warm subtropical waters, the silky shark can be found off shore, on island and continental slopes and platforms as well as in deep water reefs. Alongside with the blue and whitetip sharks the silky shark is one of the most widespread pelagic sharks.

The habitat of the silky shark is pretty vast. It ranges almost everywhere in the warm waters of the world ocean, where water temperature is no lower than 22 degrees Celsius. It can be found in the Mediterranean and the Red Sea, as well as in equatorial and the adjacent latitudes. Seasonal fluctuations of water temperature and foraging make sharks migrate in search of the better natural conditions.

Sometimes sickle-shaped sharks wander in the coastal waters; they are also often found near islands and above the submerged reefs. They can pose a threat to humans considering their large size and aggressive behavior. The warning sign for a diver an uninvited guest or a poacher, is the threatening posture, which is intrinsic to most species of requiem sharks Galapagos sharks, reef sharks and others. Shark lifts up its head, humps its back with the tail below its body. The best choice for a human is to take a hasty leave away from the area, which has become dangerous to stay in.

For fairness sake it stands to mention that there is not a single recorded case of unprovoked aggression of the shark towards humans. This means there is no point in stretching ones luck and philandering with anything but a harmless fish, moreover considering its size matching the one of a human. Although even the small size is not necessarily the attribute of peacefulness and tolerance. There are known cases of swimmers and divers being attacked by pygmy sharks no longer than half a meter, as well as leopard sharks and the tiniest cigar sharks. The same law of the jungle is applicable to marine creatures, where the winner takes it all and the role of prey awaits the weak and helpless. Therefore, when encroaching on someone elses territory, you better not violate these laws, but preserve the harmony of the underwater world.

The predator keeps to itself without uniting into schools on moderate depths up to 50 meters in the warm water layers, but it can also swim much deeper up to 500 meters down. Sometimes in order to hunt fast pelagic fish more effectively it joins the schools of tuna.

Like all the other requiem sharks, the silky sharks are viviparous. Babies are born already developed 70-80 cm in size. There can be 2 to 14 of them in one brood. Babies spend their first days in the shallow water flying the nest from the very beginning. Their mother does not experience tender sentiments towards them and does not take any part in nurturing. She could well dine on her newborn babies, if the wise nature hadnt taken care of quashing the sharks hunger during pregnancy. The average lifespan of silky sharks is around 23 years.

In many parts of the world the silky sharks are of great importance for commercial fishing. They are often caught in the tuna nets in the Gulf of Mexico, although they are also caught deliberately. The silky shark trade is pursued in the Maldives and the Caribbean Islands, USA and Japan. The silky shark is highly valued; it accounts for 70-80% of the total harvest of sharks. This fish is prized for its liver oil, tasty meat and large fins, which can be eaten dried, salted or fresh. Shark fin soup is a renowned delicacy. The silky shark is among three most important species of commercial fish in the global harvesting of shark fins. The annual recovery is 0.5-1.5 million sharks.

Due to a long pregnancy period the silky sharks, just as the other sharks, breed slowly. Small number of babies in a brood as well as their slow growth and low survival percentage also influence the tangible decrease in population of this species in the ocean. According to some reports, the population of silky sharks has dropped 85% in the last 20 years. If no measures limiting the uncontrolled fishing are taken, the silky shark may well become an endangered species in the nearest 10 years. This shark is not enlisted in the Red Book at the moment, although if such a tendency will continue for some 5-6 years, who can tell, what will happen to this marine beauty eventually. Apart from the fishing industry, the silky shark is also a target of interest for scientists, who use it in the research studies. The spotlight is on the sensory abilities of the silky predators.

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