If you've ever wondered how worms live, you've probably noticed that they look a little bit different than other critters. There are a few facts about earthworms that you should know. Here's some information about their phylum and their body plan. In fact, the body plan is tube-within-tube. This means they are segmented both internally and externally, and they are usually segmented with setae on all their segments. Their distribution ranges across the globe where soil, water, and temperature are common. Among the interesting facts about earthworms are the size and shape of their bodies. Some species are tiny and only an inch or two long. Others grow to be several feet long, and some live up to eight years. Their full size varies wildly, from less than half an inch to over 10 feet. A homegrown worm may grow to be as long as 14 inches long. In the last ice age, glaciers completely wiped out the majority of earthworm species. Despite their size, earthworms do not have ears. Charles Darwin performed experiments to test the ability of earthworms to hear. He found that they responded to vibrations and sound waves from their habitat. Then, he found that they were capable of escaping predators when they were trapped underground. Hence, if you're planning a trip to the woods or the beach, be sure to pack a bag for the worms to scurry out of danger.