Sharks can sense a drop of blood from 2.5 miles away.
They can detect one part of blood in 100 million parts of water.
Sharks, in their 400 million years on earth, have shown an extraordinary ability to resist cancer and other diseases. This has raised hopes among medical researchers that the oceans' most feared predator might turn out to be the cancer patient's best friend. Investigators continue to study the immune system of sharks to see if it can provide the answer to stopping the spread of cancer in humans.
Sharks can live up to 100 years.
The biggest shark is the whale shark which can be up to 50 feet (15 m) long. It has approximately 300 rows of teeth, with hundreds of tiny teeth in each row. It's a filter feeder and sieves enormous amounts of plankton to eat through its gills as it swims. It is also the biggest fish in the sea.
Sharks have no bones - a shark's skeleton is made up of cartilage.
The biggest meat-eating shark is the Great White which grows to be up to 21 feet (6.4 m) long.
The dogfish sharks are named for their tendency to attack their prey as a pack of wild dogs would.
The largest egg in the world was laid by a whale shark.
The egg, 14 inches (36 cm) long, was found in the Gulf of Mexico in 1953.
Sharks can go up to at least 6 weeks without feeding.
The record for a shark fasting observed in an aquarium was a Swell Shark, which did not eat for 15 months.