Fun Science: Fun Facts

	Shark's teeth are literally as hard as steel.
	A mosquito has 47 teeth.
	Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
	Seventy percent of the dust in your home consists of shed human skin
	Fish are the only vertebrates that outnumber birds.
	A cockroach can live for several weeks without its head.
	The average human produces a quart of saliva a day -- about 10,000 gallons in a lifetime
	Elephants have been known to remain standing after they die.
	The embryos of tiger sharks fight each other while in their mother's womb, the survivor being the baby shark that is born.
	Ants do not sleep.
	Nearly a third of all bottled drinking water purchased in the US is contaminated with bacteria.
	Rats multiply so quickly that in 18 months, two rats could have over 1 million descendents.
	An Astronaut can be up to 2 inches taller returning from space. The cartilage disks in the spine expand in the absence of gravity.
	The oldest known fossil is of a single-celled organism, blue-green algae, found in 3.2 billion year-old stones in South Africa.
	The oldest multicellular fossils date from ~700 million years ago.
	The earliest cockroach fossils are about 280 million years old.
	Healthy nails grow about 2 cm each year. Fingernails grow four times as fast as toenails.
	20/20 vision means the eye can see normally at 20 feet. 20/15 is better; the eye can see at 20 feet what another eye sees at 15 feet.
	The average person has 100,000 hairs on his/her head. Each hair grows about 5 inches (12.7 cm) every year.
	There are 60,000 miles (97,000 km) in blood vessels in every human.