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.
Elephant dentition is unique. In most animals, including humans, teeth are produced from the top and bottom of the mouth. In elephants however, the teeth are developed from the back and push forward. Elephant have six sets of molars in their lifetime and as a tooth wears out through relentless grinding, another pushes forward to replace it. At birth, calves have four small developing molars which they will lose at about two years old. Each successive set of teeth will last for a longer period of time until the final set appears at about 30 years. The worn down teeth wear off into a shelf which will eventually break off and fall out.