How a Shark Lives

by Cole Vickers

A wise man once said, "Just stay still, if you stay still it can't find you."
Sharks can't see that well. Sharks can be cool and dangerous creatures.

Species of Sharks

There are a lot of Sharks in the world. There is around 465 known species of Sharks in the world. Some Sharks use up to 30,000 teeth in their lifetime, that is roughly 937 times the number of teeth the average human has. Shark teeth can last longer when they are in colder water. Also, they have skeletons made of cartilage that are more flexible a lighter than a bone. They breathe through a series of five to seven gill slits located on either side of their body.

Shark Attacks

The sharks that attack the most people is the Great White, Bull, and Tiger shark. They only kill about twenty a year. Even though they attempt to attack people, people kill more sharks than sharks kill us. People kill about 20,000,000 to 100,000,000 sharks each year due to fishing activity. Sharks don't but they do have active and restful periods. It was once believed that all sharks had to swim constantly in order to breathe.

Are Sharks Dangerous?

Only about a dozen are considered dangerous when encountered. Tiger, Bull, and Great White sharks have the most unprovoked attacks on humans. Most of the sharks in the world are very active at night which is when they hunt. Some shark species, like the great white shark, attack and surprise their prey, usually seals and sea lions, from below. Species that dwell on the ocean floor have developed the ability to bottom-feed. Others attack schooling fish in a feeding frenzy, while large sharks like the whale and basking sharks filter feed by swimming through the ocean with their mouths open wide, filtering large quantities of plankton and krill. "Sharks are beautiful animals, and if you're lucky enough to see lots of them, that means that you're in a healthy ocean. You should be afraid if you are in the ocean and don't see sharks." Sylvia Earle
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Species of shark

Sharks Age

Sharks predate the dinosaurs by 200,000,000 years. The largest known species of shark, C. megalodon, might have reached a maximum length of 67 feet. It is difficult to estimate population numbers since there are many different species spanning a large geographic area. However, overall shark numbers are on the decline due to the many threats they face in the wild. Sharks, however changed very little over time. Although lifespan varies by shark species, most sharks are long-lived and generally tend to live for 20-30 years.

What Do Sharks Eat?

Most species of shark eat things like fish, crustaceans, mollusks, plankton, krill, marine mammals and other sharks. Sharks also have a very acute sense of smell that allows them to detect blood in the water from miles away. Many sharks (like the great white, blue shark, mako, tiger shark, and hammerhead) are swift, sleek predators that eat fish, squid, other sharks, and marine mammals (like sea lions, seals, and smaller whales). Some bottom-dwelling (benthic) sharks (like the zebra horn shark, angel shark, and wobbegong) are slow-swimming predators that crush and eat shellfish (crabs and clams) from the ocean floor. Some large sharks (like the whale shark, the basking shark and the megamouth shark) are filter feeders that sieve tiny bits of plankton and small animals from the water through their gills as they swim with wide-open mouths. Sharks don't drink water!
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A shark swimming in the ocean.

Bibliography

Shark Diets - EnchantedLearning.com. (n.d.). Retrieved November 12, 2015, from http://www.enchantedlearning.com/subjects/sharks/anatomy/Diet.shtml

Basic Facts About Sharks. (2012, February 15). Retrieved November 12, 2015, from http://www.defenders.org/sharks/basic-facts

Shark Teeth. (n.d.). Retrieved November 12, 2015, from http://www.sharksavers.org/en/education/biology/shark-teeth1/

Shark Facts: Attack Stats, Record Swims, More. (n.d.). Retrieved November 12, 2015, from http://news.nationalgeographic.com/news/2005/06/0613_050613_sharkfacts.html