I think that all of North Americas sea shore critters can not be described in a single book. Certainly not in a book of this size. The publishers where quite bold in the scope and as such much information has been left out. That said let me tell you what is good about this book. The pictures are GREAT! Much better than looking at technical drawings. However, they are not better for identification. The descriptions of animal groups are excellent. For the person with little biological background this will go a good way toward explaining the complexities of ocean life. The method of identification, sorting by superficial appearance is handy, again for the inexperienced. To sum it up, if you want one book to carry during your first summer of beach combing get this one. If you need a companion for a marine zoology class stay away, unless you already have everything else.