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Did you know that sharks can’t breath unless they are moving? It sounds crazy but it's true! The gills are like the air scoops on a car’s hood. The oxygen in the water won’t get in the gills unless the shark is moving. If it stops and takes a rest for too long, it will die. |
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Sharks Did you ever wonder how sharks communicate? Well, you came to the right place. Let me tell you how they communicate! Sharks are feared by many people because they are meat eating fish. There are about 360 species of sharks. Only about one seventh of the 360 species are dangerous to humans.
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| Animal Communication |
Much
about how sharks communicate is not known. Scientists thought of Sharks actually have a “sixth sense.” With it they can detect electric fields to capture their prey. The US Navy actually used sharks to detect underwater mines and submarines! Isn’t that cool? For underwater creatures, sharks have good senses. But remember that is… for an underwater creature.
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| Physical Characteristics |
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Sharks aren’t all the same. For example,
they come in many sizes and shapes such as Sharks don't have an organ that fish have called a swim bladder (an organ filled with gas to help fish float). Instead, they have a liver filled with oil that is less dense than water. Even with this organ, sharks have to swim without stopping, or they will sink!
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| Habitat |
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Sharks
live in the oceans around the globe and are most commonly found in warm seas. There has been a shark called a zambizi shark, found
in a river, but that is not its natural habitat. Sharks also live
in all different levels of the ocean. Some are found near the ocean
floor and some near the surface. For example, angel sharks are found
near the ocean floor.
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| Food |
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Sharks
eat fish, seals, other sharks, and sting rays. Sharks almost always eat
smaller sharks but are scared of the bigger ones. Shark attacks on people
are rare. Sharks hate people; they taste awful. You are more likely to
die driving to the beach than getting eaten by a shark!
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| Growth & Reproduction |
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Sharks reproduce
differently than most fish. They do not produce large amounts of
eggs and larvae (most of which do not reach maturity). Instead
sharks normally produce about a dozen pups, but it really varies.
Some species have up to 70-80 pups and some as few as 2-3 pups.
Sometimes the pups are born alive, and sometimes they are protected by
egg cases. Sharks do not make good parents! They have never been known
to stay with their young. When a female shark gives birth to a
pup, a hormone is released into her blood that stops her from feeding.
However, some parents have been known to eat their young!
Unlike most fish, a shark's eggs are fertilized inside the female's body. For most sharks, the eggs actually hatch inside the female's body and then the pups are born alive. There are also about 40 species of sharks that lay eggs outside the female's body.
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| Other Interesting Facts |
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| Citations |
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Online Source Bright,
Michael,
"
Shark Behaviour." Jaws, the Natural History of Sharks.
February, 2006 "Island
of the Sharks." Nova Online, PBS. February, 2006 Parker,
Jane and Steve.
The Encyclopedia of Sharks.
February, 2006
Ritter, E.K., "Communicating with Sharks." Sharkinfo, International Media Services. February, 2006 <http://www.sharkinfo.ch/SI1_01e/communication.html>. "Why a Whale
Shark's Spots Could Help Save Its Skin." Shark Research
Institute. February, 2006 <http://www.sharks.org/pdfs/spots_save_skin.pdf>. Images Permission to use photograph of whale
shark is granted under the terms of the GNU
Free Documentation License from Wikipedia, the Free Encyclopedia. February,
2006 <http://en.wikipedia.org/wiki/Main_Page>. |
sharks as “eating machines,” and they thought sharks didn't communicate. One
leading marine scientist, Peter Kimley, suggested that sharks communicate, and he was laughed at! But after the incident,
researchers found that sharks did communicate, and they mostly used
movements and actions. For example, when they circle, they’re
preparing to attack. 
the tiger shark (21
feet long) and the silver-tip shark (9 feet long). There are more than 368
types of sharks! Sharks, unlike fish, are made of cartilage. Fish
are made of bones. The largest and rarest shark is the whale shark.
It has a mouth shaped like a whales. That’s why it’s called a
whale shark. Sharks use their lower fins to balance, and rear fin (tail)
to move. Sharks are very well known for the fin on top of them.