sharkfacts.txt

Sharks live in every ocean on the planet.
Sharks have eight orders of classification depending on their physical characteristics.
Sharks are cartilaginous. What makes sharks different from fish is that their skeletons are made of cartilage instead of bone.
Sharks are also different from bony fish because they have eyelids.
Another thing that makes sharks different from fish is their scales. Sharks have dermal denticles also called placoid scales, which are smooth and help them move quickly through the water. Fish have flat, rough scales.
Unlike fish, sharks can only swim forward. That is because their fins are stiff and cannot be controlled by muscles.
Sharks stay buoyant because of their light weight cartilage skeletons. They also have really oily livers which helps them stay balanced in deeper waters.
An average shark has 40-45 teeth in up to seven rows. Sharks lose teeth regularly and can go through 30,000 teeth in their lifetime.
Sharks have been living in Earth’s oceans for 450 million years.
The smallest shark is the dwarf lantern that is only grows to six inches and the largest is the whale shark that grows to a whopping 41.5 feet in length.
The largest shark to ever live was the massive Megalodon that averaged 50 feet in length. Don’t worry though, these terrifying sharks have been extinct for 16 million years.
The oldest known species of living shark in the goblin shark that has been around for 120 million years. The second oldest is the frilled shark that has been around for 80 million years.
You can measure the age of a shark by counting the rings on its vertebrae.
Most sharks never sleep because they have to constantly pump water through their mouth over their gills to breath or they will die.
Sharks have an amazing sense of hearing. They can hear prey up to 3000 feet away. Their ears are actually located inside of their heads.
Scientists think sharks may be color blind. However, they have eyes similar to cats and can see better in dark and murky waters than other fish.
Sharks eyes are located on the sides of their heads to give them a wider view of their surroundings.
Some sharks living in frigid waters can heat their eyes with a special organ in their eye socket so they can hunt more efficiently regardless of the temperatures.
Sharks living deep in the water tend to have light color eyes to help them attract more light, while sharks living closer to the surface have darker colored eyes to shield them from the light.
Sharks rely on electroreception to navigate the ocean and notice prey.
Sharks can move both their lower and upper jaws.
Sharks whip their prey around back and forth in order to break off large chunks of meat.
Sharks have the thickest skin of any animal species. Some sharks have skin that is 6 inches thick.
Sharks have the largest brains of any fish.
Sharks communicate through body language. Some common communications involve zigzag swimming, head shaking, hunched backs, and head butts.
Sharks do not have vocal cords, so they make no sounds. That is why they are known as the “silent killers.”
Large sharks live longer than smaller sharks.
Size also determines where a shark hunts. Smaller sharks tend to hunt along the ocean floor, while larger sharks hunt in the middle and by the surface.
Sharks have few natural predators. Killer whales, seals, crocodiles, and larger sharks will occasionally eat sharks. The biggest threat to sharks is humans.
Sharks have been known to reproduce assexually. This is known as parthenogenesis and has been documented in a variety of different species.
One of the most common ways sharks mate is by biting each other.
The youngest species of sharks are the hammerheads, which evolved on 20 million years ago.
Some species of sharks are carnivorous in the womb. The first tiger shark pup to hatch will eat its siblings.
Most female sharks will lose their appetites before giving birth. This is a biologically trigger to prevent them from eating their own pups.
Frilled sharks have the longest gestation period. They are pregnant for 3 and a half years.
Bull sharks can live in both fresh and saltwater.
Nurse sharks are the laziest sharks. They rarely migrate and eat less than most sharks. They also do not need to move to breath like other sharks.
Most sharks hunt alone. However some species like scalloped hammerhead sharks hunt in packs.
Basking sharks also rarely travel alone. Typically they travel in pairs but have been seen in schools of 100.
Great white sharks eat an average of 11 tons of food a year. Though they can go as long as three months without eating.
Great whites can jump out of the water up to ten feet to catch their prey. This is done to beat the competition for food.
Blue sharks are the most endangered species on the planet. Blue sharks are highly coveted for their fins used in shark fin soup.
Lantern sharks use bioluminescence making them glow in the dark. They use this trick to attract mates and confuse their prey.
Angel sharks can ambush their prey in one-tenth of one second.
Thresher sharks use their tails to slap their prey to death.
Bamboo sharks don’t swim. They use four different fins to walk across the ocean floor.
Sixgill sharks can have litters of 100 pups.
Shark attacks are extremely rare and account for four fatalities every single year worldwide.
Humans kill 100 million sharks a year. That means for every single person killed by a shark, humans kill 25 million sharks
Most sharks do not like the taste of humans, so they most often just take a bite and swim away disinterested.
Sharks respond to a sound known as a "yummy hum". It's an infrasonic sound that injured fish make, drawing sharks to an easy meal.
Swell sharks have biofluorescent properties that let their skin glow green.
Sharks have no bones. So when they die, the saltwater dissolves every part of them except for their teeth.
Bull sharks can regulate their salt retention, which allows them to survive in both fresh water and salt water.
The Greenland shark is the only species that can tolerate Arctic temperatures year round.
Frilled sharks have 25 rows of razor sharp teeth.
Pygmy sharks only grow to be about seven or eight inches long.
Sharks are able to feel vibrations in the water using a line of canals that go from its head to its tail. Called a "lateral line", these canals are filled with water and contain sensory cells with hairs growing out of them. These hairs move when the water vibrates and alerts the shark to potential prey.
According to the World Conservation Union, 20 to 30 percent of sharks are close to extinction.
Sharks are one of the most threatened groups of vertebrates on the planet.
Sharks can generate up to 40,000 pounds per square inch of pressure in a single bite.
Whale sharks can give birth to 300 pups in a single litter.
Sharks likely predate both humans and dinosaurs.
Their seriously sharp teeth are immune to cavities thanks to a protective fluoride coating.
Though sharks are known for their excellent hearing, their ears are actually embedded within their heads.
Shark skin is made up of tooth-like scales called dermal denticles, which help sharks swim quickly and quietly.
Punching a shark in the nose or poking its eyes won’t help to fend it off. It's better to aim for the gills — or, if your aim is off, the much bigger target of the snout. Most sharks don’t want to work that hard for their food and will swim away.
Shark teeth aren't used for chewing; they're just for snapping, crushing and maiming prey.
Scalloped hammerheads just became the first species of shark listed on the endangered species list.
While some shark species have a gestation period that lasts for several months, spiny dogfish sharks carry their pups for almost two years.
Only 20 shark species are known to attack humans.