How many hammerhead shark attacks

Carcharhinus limbatus. Carcharhinus longimanus. Carcharhinus melanopterus. Carcharhinus obscurus. Carcharhinus perezi. Carcharhinus plumbeus. Carcharias taurus. Carcharodon carcharias. Galeocerdo cuvier. Galeorhinus galeus. Ginglymostoma cirratum. Heterodontus portusjacksoni. The worldwide total of 57 confirmed unprovoked cases was lower than the most recent five-year average of 80 incidents annually.

There were 13 shark related fatalities this year, 10 of which were confirmed to be unprovoked. This number is above the annual global average of four unprovoked fatalities per year. Annual fluctuations in shark-human interactions are common. Year-to-year variability in oceanographic, socioeconomic and meteorological conditions significantly influences the local abundance of sharks and humans in the water.

Consistent with long-term trends, the United States experienced the most unprovoked shark bites in , with 33 confirmed cases. This is Eight bites occurred in New South Wales, two of which were fatal. Three bites occurred in Queensland, two of which were fatal. Five bites occurred in Western Australia, two of which were fatal. Single incidents occurred in South Australia and Victoria. Here's the good news: You don't have to worry about a blue shark stalking you while you frolic in the waves a few yards from your beach blanket.

This aquatic predator, who can grow in excess of 12 feet 3. That's where it finds its dinner: small bony fishes, like herring and sardines, and invertebrates, like squid, cuttlefish and octopi.

It's also been known to scavenge on dead marine animals and steal from fishermen's nets. And that brings us to the bad news: Although blue sharks aren't known to be particularly aggressive -- especially compared to their nastier cousins the bull sharks -- they won't always turn their noses up at a potential meal of human flesh, either, if you happen to be shipwrecked or floating on your seat cushion after surviving a plane crash. Reportedly, blue sharks have circled unfortunates bobbing around in their feeding grounds, and have been known to take exploratory bites [source: Florida Museum of Natural History ].

That said, between and , there've only been 32 just 32! In reality, blue sharks Prionace glauca have far more to fear from people. An estimated 10 to 20 million of them are killed by humans each year. Many blue sharks are killed when they become entangled in fishermen's nets and others are slaughtered for their fins, which are sold on Asian markets for making shark fin soup, a delicacy [source: Florida Museum of Natural History ].

If you're a Florida surfer, you may already be familiar with the blacktip shark Carcharhinus limbatus , since the species reportedly inflicts 16 percent of the shark bites on surfing enthusiasts in your state. Blacktips also have chomped on humans along other parts of the Atlantic and Gulf coasts of the United States, and off the waters of South Africa and the Caribbean. If there's an upside to this, it's that the species, which prefers depths of around 10 feet, only averages about 5 feet 1.

There've been 42 documented attacks on humans by blacktip sharks, but just one resulted in an unprovoked fatality [source: International Shark Attack File ]. Though blacktips usually prefer saltwater, they also are often seen near shore around river mouths, bays, mangrove swamps and in other estuaries. They get their name from the distinctive black markings on the tips of their fins.

They have stout bodies with a moderately long, pointed snouts and high, pointed first dorsal fins. They're dark gray-blue or brown on their upper bodies, with white underbellies and a distinctive white band across their flanks. Blacktips feed primarily on small schooling fishes like herring and sardines, but they also eat bigger bony fish like catfish and grouper and have been known to make a meal out of some types of small sharks, stingrays, crustaceans and squids.

We'd be remiss if we didn't add that like many other shark species, blacktips have more to fear from humans than the other way around. They're caught by fishermen, who sell their meat for human consumption or to be used as fish meal to feed animals. Their fins are also sold in Asian markets for making soup. The director of the ISAF warns that these statistics aren't perfect. Shark attacks in the third world are rarely reported to the ISAF. Some sharks are simply more identifiable than others, so their statistics might be much higher than the "hit-and-run" sharks, sharks that take a quick bite and then disappear.

Some of the more easily identified sharks are the great white, tiger, sand tiger, hammerhead and nurse sharks ; the most difficult sharks to identify are some members of the family Carcharhinidae, or the requiem sharks. Requiem sharks as a grouping take fourth place in the ISAF's attack statistics. If the nurse shark were a person, it might have a chip on its shoulder about its name, which isn't nearly as ferocious-sounding as "bull" or "tiger.

The species Ginglymostoma cirratum , which grows to between 8 and 9 feet 2. Fortunately, even in the rare instances when a nurse shark does attack a human -- so far, 52 times, with no recorded fatalities -- the bite isn't powerful enough to be lethal [source: International Shark Attack File ]. The downside is that the nurse shark's small mouth is attached to a large pharynx that enables it to suck up food and latch onto it.

In fact, its grip is so vicelike that, in some cases, rescuers have had to use surgical instruments to free victims. Fortunately, humans aren't the nurse shark's preferred meal, of course; the species feeds mainly on stingrays, octopi, squids, clams and crustaceans. They're nocturnal animals that rest on sandy bottoms or in caves and crevices during the day, and they often gather in groups of as many as Nurse sharks have rounded, stubby heads with set-back eyes, and long caudal tail fins, which account for more than a quarter of their total length.

They range from light yellowish tan to dark brown in color, and young nurse sharks have small black spots on their bodies. While nurse sharks are not endangered, their population in Florida has decreased in recent decades. Requiem sharks actually are a family of 12 genera and approximately 50 species. They have a funereal-sounding name, and for spear fishermen, in particular, they can be a lethal menace.

That's because fish skewered and struggling on a spear emit low frequency vibrations, which requiems can detect with their highly sophisticated sensory organs. Once they've arrived in the vicinity of the catch and can smell blood, their aggressive instincts can take over. That's not a good thing, if you happen to be in the water with them, because the strong-swimming, torpedo-shaped predators, who travel either solo or in groups, have big mouths filled with sharp, serrated teeth [source: Randall ].

Various types of requiem sharks have attacked humans 56 times, with seven unprovoked fatal attacks on record [source: International Shark Attack File ]. What makes the sharks even more frightening is that a few of requiem species, such as the grey reef shark, have a distinctive threat posturing. The sharks will swim laterally, toss their heads in an exaggerated fashion, arch their backs with their pectoral fins held downward, and snap their jaws menacingly.

If you see a shark doing that, it's best to move slowly away. Requiem species vary in size, but the biggest can exceed 24 feet in length, often making them the biggest bullies on the block [source: Beller ]. If there's a silver lining to all this, it's that requiems are voracious eaters who normally dine on a lot of other creatures besides humans, including sharks and rays, squid, octopuses, lobsters, turtles, marine mammals and sea birds [source: Randall ].

Large and fierce members of the Requiem family, like the bull shark and the tiger shark, are especially dangerous to humans. We'll get to them in a couple of pages. Researchers who've observed sand tiger sharks say they generally aren't aggressive toward humans unless provoked, but that's not much consolation if you're a fisherman and find yourself confronted with the predator's prominent, jagged-looking teeth [source: Florida Museum of Natural History ].

Sand tigers have attacked humans 77 times, though, miraculously, only one of the attacks proved fatal [source: International Shark Attack File ]. The species Carcharias Taurus is found in most warm seas throughout the world, except for the eastern Pacific. In the western Atlantic Ocean, sand tiger sharks range from the Gulf of Maine to Argentina, and are commonly found in Cape Cod and Delaware Bay during the summer months.

They're most often found close to shore, at depths ranging from 6 to feet 1. Sand tiger sharks are large and bulky, with flattened conical snouts and long mouths that extend behind the eyes; they sometimes have dark reddish or brown spots scattered on their bodies. Females can reach a maximum length of more than 10 feet 3 meters ; males are usually just under 10 feet. As previously mentioned, sand tigers have a hearty appetite -- for herrings, mullets and rays, among other things -- and they sometimes hunt in schools and cooperate by surrounding and bunching their prey.

Sand tigers are fished for food in the north Pacific, northern Indian Ocean and tropical west coast of Africa. The sand tiger shark is dangerous before it's even born! It eats its brothers and sisters in the womb, something an unsuspecting researcher discovered the hard way when he stuck his hand in there [source: Parker ].

Tiger sharks aren't looking to specifically eat humans, but then, they weren't specifically looking to eat lumps of coal, cans of paint, packs of cigarettes or Senegalese drums either. These items have all been found in the bellies of tiger shark s Galeocerdo cuvier , which are known for their ability to eat just about anything [source: Parker ]. So while other sharks may just want a sample to find out if a person is edible, the tiger shark is less likely to let go once it's taken a bite.

If a tiger shark does decide to continue eating, you're in for an unpleasant experience, to say the least. Their jaws have elastic muscles , which allow them to swallow pieces of prey much larger than what might seem possible.