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Basic Shark Facts For Scuba Divers - Part 1 of 3

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photo of a Caribbean reef shark swimming underwater.

Sharks can sense electromagnetic fields.

© istockphoto.com

Shark Basics | 6 Ways to Save Sharks From Extinction | Sharks Main Page

For many people, the word "shark" conjures the image of a dangerous animal, a killing machine out to attack humans. This could not be further from the truth. In fact, a person is more likely to be struck and killed by lightening than attacked by a shark. Worldwide, sharks only kill 4 - 5 people a year. Instead of fearing sharks, divers should realize that sharks are fascinating animals that play an essential role in maintaining balance within marine ecosystems. Here are some interesting facts that divers should know about sharks.

Are Sharks Fish?:

Although sharks, skates, and rays do not have scales, they are still classified as fish. These creatures are all members the cartilaginous fish group; instead of bones, their bodies are supported by cartilage (like a person's nose). Cartilage is more flexible than bone, giving shark fins an almost rubbery appearance. As migratory fish, sharks spend most of their time in open water. With more than 400 types of sharks on the planet, shark species demonstrate great diversity in size, appearance, habitat, and behavior.

Sharks Frequently Lose Teeth:

One of a shark's most recognized characteristics is a mouth of sharp, scary teeth. As an apex predator (meaning that sharks are at the top of the food chain), a shark's teeth need to meet the challenge of eating the wide variety of animals below it on the food chain. Without teeth, a shark would be unable to survive, so sharks have an interesting way of dealing with broken or lost teeth. Shark teeth are embedded in the animal's gums and can come out of a shark's mouth relatively easily. Rows of replacement teeth grow along the jaw and move forward when a tooth needs to be replaced.

Do Sharks Really Eat Humans?:

With a keen sense of smell, sharks can detect blood in the water in quantities as little as one part per million. Sharks have very specific food preferences and humans are not at the top of their menu. A shark will either vomit out an unfavorable food item or its stomach will turn inside out to eject it. Of over 400 shark species, great white, tiger and bull sharks are responsible for the majority of (the very few) attacks on humans. Learn more about shark attacks and scuba diving.

Sharks Have a Sixth Sense:

Sharks have a network of jelly-filled pores which are used to detect electromagnetic fields produced by other animals. This can be though of as a sixth, "electromagnetic sense". A shark's electromagnetic sensing cells are known as the ampullae of Lorenzini, and can help a shark to find its next meal. Sharks are the most electrically sensitive animals on the planet, and are even capable of finding prey hidden in sand by honing in on the prey's electric field. Sharks can also sense the electric fields generated by ocean currents, aiding them in navigating the ocean.

Fun Sharks Facts and Trivia:

• A shark on land would be crushed by its own weight. Sharks lack a ribcage to maintain body structure.

• Most sharks have eight fins. Despite this, they cannot back up. Their fins do not allow them to move tail-first, which means they eventually drift over objects directly in front of them.

• Despite its numerous teeth, a shark's digestion is very slow.

• Many shark species must maintain constant motion to keep water flowing over their gills. If they stop swimming, they do not receive sufficient amounts of oxygen to survive.

Part 1: Shark Basics and Trivia | Part 3: 6 Ways to Save Sharks From Extinction | Home: Sharks Main Page

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