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.
Sharksâ teeth are arranged in series; when one tooth is damaged or lost, it is replaced by another. Most sharks have about 5 rows of teeth at any time. The front set is the largest and does most of the work. A bull shark might have 50 ârowsâ of teeth, with 7 teeth in each ârowâ (one for each series). This would therefore be 350 teeth (approximately, since some rows might be incomplete). On average, sharks can lose about 30,000 teeth in a lifetime.