But fortunately for most of us, the immune system is constantly on duty to battle germs that could make us ill. The following discussion questions and activities will help your students learn about how the immune system protects them from germs and illness.
Elephants however, go through six sets of 9lb teeth during their lifetimes, with new teeth growing in to replace old ones that have worn out. An elephants starts with two front teeth that fall out after about a year and are replaced by a set of tusks.
An adult alligator has between 74 and 84 teeth in its mouth. Alligators don't chew and their teeth aren't particularly sharp, but taken together, they are very effective. If a tooth wears down or breaks off, a new one grows to take its place. It is believed that alligators go through 2,000 to 3,000 teeth in a lifetime.