Hermit crab species differ widely from one another. Some are only a few millimeters long, whereas others can grow to be the size of a coconut. Similarly, their life spans can range anywhere between ten and eighty years. On the whole, there are six different families and over 1,000 species of hermit crabs that are contained in the superfamily Paguroidea. 4.72 W x 2.56 H. Non-toxic and BPA free. Ages 3 and up.